THE PHYSICAL AND HISTORICAL FRAMEWORK - … fissure in Earth's crust (the Rio Grande rift) that is six times deeper than the Grand Canyon and thirty times larger than the Rio Grande

C H A P T E R O N E

THE PHYSICAL AND HISTORICAL FRAMEWORKD E C I S I O N - M A K E R S

F I E L D C O N F E R E N C E 2 0 0 5T a o s R e g i o n

Photo not available online

DECISION-MAKERS FIELD GUIDE 2005

C H A P T E R O N E6

© W

ILLI

AM

ST

ON

E

Rio Grande gorge and Taos Mountains.

Photo not available online

MINING IN NEW MEXICO

With the geologist lies the special responsibility andopportunity of revealing the earth in all its beauty andpower. … If geology and the geologist neglect interpre-tation of the earth to society, they are guilty of relin-quishing what should be one of their major contribu-tions. —David Leveson, A Sense of the Earth

Taos is located at the edge of radically differentlandscapes. The town is situated on the eastern

edge of a broad, high valley known as the TaosPlateau. The Taos Plateau forms the southern part ofthe San Luis Basin, part of the Rio Grande rift. Thebasin is flanked on the east, south, and west by high-lands of the southern Rocky Mountains. To the east isthe Taos Range of the southern Sangre de CristoMountains. To the south are the Picuris Mountains, awestward prong of the Sangre de Cristo Mountains.The western highland is called the Tusas Mountains orthe Brazos uplift. Geologic processes, working steadilythrough many millions of years, have contributed tothe formation of these contrasting landscapes.

The quietude of the Taos Plateau belies the tumul-tuous geologic history of the region. Taos is located inone of the most dynamic and stimulating geologic set-tings on the planet. Buried beneath the plateau is anenormous fissure in Earth's crust (the Rio Grande rift)that is six times deeper than the Grand Canyon andthirty times larger than the Rio Grande gorge. The riftcontinues to be active, as indicated by the commonoccurrence of small to moderate earthquakes and thepresence of large chambers of molten rock at depth.Evidence of past catastrophic seismic and igneousevents is visible from most anywhere in the Taos area:young fault scarps where the mountains join theplateau, and a profusion of volcanoes and lava flowsin the basin. Fortunately for us, neither destructiveearthquakes nor volcanic eruptions have occurred inthe historic past, although both will undoubtedlyoccur in the future.

The mountains, valleys, and volcanoes convey a taleof past landscapes that have evolved dramatically andrepeatedly during the last 2 billion years, from shallowtropical seas to vast, sand-duned deserts; from enor-mous white sand beaches to muddy meandering rivers

and lush fern forests; and from enormous mountainranges to flat, featureless plains. These geographic fea-tures—the bold mountain escarpments, the fertile,flood-prone valleys, the deep gorge, and the dry table-lands—have greatly influenced 10,000 years of humanoccupation.

GEOLOGY OF THE MOUNTAIN RANGES

The three mountain ranges that surround the TaosPlateau are the southernmost surface expression of theRocky Mountains. In New Mexico, this area has a longhistory of repeated uplift, erosion, and burial. The lat-est uplift began approximately 70 million years agoduring the Laramide orogeny and continues today. In

T H E P H Y S I C A L A N D H I S T O R I C A L F R A M E W O R K 7

The Geology and Landscape of the TaosRegion

Paul Bauer, New Mexico Bureau of Geology and Mineral Resources

Landforms and Landscapes

A landform is any natural, discrete surface feature witha characteristic shape. A landscape, however, is a

unique, distinct cluster of landforms. Mountain slopes,mountain valleys, and mountain peaks are landforms,whereas mountain belts are landscapes; volcanoes,calderas, craters, and lava plains are landforms, whereasvolcanic fields and volcanic plateaus are landscapes.

All landforms have geological underpinnings. Mostlandforms are formed by a sequence of highly complexgeological systems or processes, many of which are notvisible or evident at the surface of the earth. Furthermore,all landforms have been modified to some extent. Somelandforms in the Taos area, such as the 2.7-million-year-old Ute Mountain volcano, have maintained most of theiroriginal shapes. Other landforms have been significantlyaltered from their original forms by the processes ofweathering and erosion. The Taos Plateau has been exten-sively modified by the Rio Grande and its tributary riversto form the modern canyon system.

It is important to make a distinction between the age ofa landform and the age of the materials that compose thelandform. The rocks that form Wheeler Peak are nearly1.8 billion years old, whereas the uplift of the Sangre deCristo Mountains is about 60 million years old, and thedramatic crags of the Wheeler Peak area were sculpted byglaciers that melted only about 12,000 years ago.


the Taos area the Sangre de Cristo Mountains exposethree principal ages of rocks:

• Precambrian metamorphic rocks (1.8–1.4 billionyears old)

• Pennsylvanian sedimentary rocks (about 300million years old)

• Tertiary igneous rocks (26–18 million years old)

The Tusas Mountains contain only the Precambrianand Tertiary assemblages, whereas the PicurisMountains are composed entirely of Precambrianrocks.

In general, Precambrian rocks are dense and strongand highly resistant to erosion. Consequently, in theTaos area, most of the highest mountain peaks andsteepest slopes are composed of such rocks. Theyinclude a wide variety of rock types (granite, gneiss,quartzite, schist) and ages, including the oldest datedrock in New Mexico, near Wheeler Peak.

Even though Precambrian rocks represent morethan 80 percent of the history of our planet since itsformation 4.5 billion years ago, our knowledge ofPrecambrian geology is woefully incomplete.Precambrian rocks now exposed at the surface in theTaos area were deeply buried during much ofPrecambrian time, and we know little of what washappening at the surface. We do know that the crustwas subjected to intense metamorphism, folding,faulting, and melting during the lengthy formation ofthe North American continent until about 1 billionyears ago. These ancient rocks are easily seen in manyplaces near Taos: at Taos ski valley, Ponce de Leon hotsprings, Red River Pass, on top of Wheeler Peak, inthe steep cliffs near Pilar, and in the hills behind theOjo Caliente hot springs.

Precambrian rocks supply much of the mineralwealth in the Southwest, and such is the case in theTaos region. The distinctive, micaceous clay prized byPicuris Pueblo potters is derived from a Precambrianschist from the Picuris Mountains. The controversialmica mine south of Taos is located in a similardeposit. Precambrian quartzite hosts the rich copperveins at Copper Hill near Peñasco. Gold was minedfrom Precambrian rocks near Red River. Copper wasmined at Twining (now Taos ski valley) around 1900.The schists of the Picuris Mountains contain the “fairycross” staurolites sold in local mineral shops. TheHarding pegmatite mine near Dixon is a world-famousmineral collecting locality and has produced impor-tant amounts of the rare metals lithium, beryllium,

tantalum, and niobium. Suggestions of gold and silverdeposits have periodically piqued the interest ofprospectors and speculators in the Hopewell Lake areaof the Tusas Mountains.

From 1.4 billion years ago until the MississippianPeriod (354 million years ago) there is no rock recordto study. Where rocks are absent, geologists mustdetermine whether sediments were not deposited, orwhether sediments were deposited and later eroded.In general, an advance of the sea promotes sedimenta-ry buildup, whereas a retreat of the sea and exposureof the landmass to the air promotes erosion. Becausesediments of Cambrian to Devonian age are absent innorthern New Mexico but present to the south, geolo-gists infer that during that time the Taos area was alandmass, and southern New Mexico was ocean.

During Pennsylvanian time, 80 percent of NewMexico was submerged beneath warm, shallow, equa-torial seas. Northern New Mexico probably resembledmodern-day North Carolina, with a flat coastal plain,swampy forests, and high mountains to the west.Mud, silt, sand, and gravel were eroded from nearbyisland highlands into a large sedimentary basin knownas the Taos trough. Over time, as the thousands of feet


Physiographic map of the Taos region.



of sediments were buried and compacted, theyevolved into the sedimentary rocks that we now seeeast and south of Taos. These limestones, siltstones,shales, sandstones, and conglomerates are exposedover most of the southern part of the Sangre de CristoMountains, with excellent exposures on NM–64 alongthe Rio Fernando and along NM–518 south of Talpa.

A close examination of the Pennsylvanian rocksexposed near Taos reveals evidence of their originalenvironments of deposition (rivers, deltas, shorelines,tidal flats, shallow seas), including features such asripple marks, raindrop imprints, and crossbeds. Thewarm Paleozoic seas teemed with ancient life, andpaleontologists have classified the fossilized remains ofhundreds of marine species in the Taos area, includingmany varieties of clams, snails, sea lilies, corals, andbrachiopods.

During Pennsylvanian time the region was subjectedto a major mountain-building event known as theAncestral Rocky Mountain orogeny. Today the mostapparent effects of this are tilted and faultedPennsylvanian strata. The modern Rocky Mountainsmimic the chain of mountains that developed inPennsylvanian time, because once the crust is brokenit remains a zone of weakness to be exploited by laterpulses of mountain-building events.

Mesozoic rocks do not exist in the Taos area,although they are exposed in the Moreno Valley nearAngel Fire. The Triassic and Jurassic Periods (248–144million years ago) were characterized by deposition ofnonmarine sandstone and shale over much of north-ern New Mexico. Until very late in Mesozoic time, thisarea was alternately land and sea, as the shorelineadvanced and retreated over a low-relief landscape.Great thicknesses of shale, sandstone, and limestoneaccumulated in these vast Cretaceous seas, and attimes, much of the state was submerged. Sharks teethare common Cretaceous fossils in New Mexico.Dinosaurs roamed the lush landscape of shorelines,river valleys, and widespread swamps for over 100million years, until the great extinction 65 millionyears ago.

From Late Cretaceous time to early Tertiary time theTaos region was squeezed by forces associated withthe next great mountain-building event, the Laramideorogeny. Compression of the crust resulted in majoruplift and erosion and development of folds andfaults. The western half of the Taos trough was uplift-ed and eroded, and by Tertiary time only rolling hillsremained. Later, during Oligocene time, the San LuisBasin began to subside, while the Sangre de CristoMountains began to rise. Volcanoes erupted in the

uplifted area, covering the region with lava and ash.The largest volcanic event was the explosive eruptionof the Amalia Tuff from the Questa caldera about 25million years ago, approximately coincident with theonset of the next great event, Rio Grande rifting.

The Bear Canyon pluton, visible in Red RiverCanyon, is one of many magma bodies that wereemplaced in the Questa area following the calderaeruption. Collectively, these igneous rocks make upthe “Questa magmatic system.” As the magmas cooledand solidified, mineral-rich hydrothermal fluids perco-lated through the rock, and minerals such as molyb-denite, quartz, and pyrite were precipitated in smallfractures. These fracture-fillings (veins) later becamethe targets of prospectors and miners. Veins of themineral molybdenite (molybdenum sulfide), an ore ofthe metal molybdenum, are found in unusually highconcentrations in the Questa/Red River area and arenow mined by Molycorp for use as lubricants and inthe manufacture of stainless steel.

During the past 20 million years, the mountainshave continued to rise and erode as the continentalcrust has continued to extend. By Pleistocene time(1.8–0.01 million years ago), the Sangre de CristoMountains had mostly developed their modern form.

Block diagram showing the principal geologic elements of theRio Grande rift in the the Taos area. A deep sedimentary basin(San Luis Basin) has formed in the crust above a bulge of hotasthenosphere. The Rio Grande has eroded a deep canyon inthe rift basin. Not to scale.



During the Pleistocene ice ages, glaciers covered thehigher peaks, scouring out depressions called cirques,and dumping huge volumes of sediment-laden waterinto the San Luis Basin.

GEOLOGY OF THE RIO GRANDE RIFT, SAN LUISBASIN, AND TAOS PLATEAU

Taos is situated in one of the few young continentalrift valleys on Earth. The other great rift valley is the4,000-mile-long East African rift, which, as it has torneastern Africa apart, has created Africa's highest peaks,deepest lakes, and equally impressive landscapes.The Rio Grande rift is part of a global system of frac-tures in Earth's uppermost rigid layer (the lithosphere)that have formed in order to accommodate relativemovements of the lithospheric plates. The lithosphereis broken into about a dozen major plates that moveover an underlying layer of partially molten rocks (theasthenosphere). Although most of the activity associat-ed with plate tectonics occurs at or near plate mar-gins, in some cases, such as along the Rio Grande rift,activity occurs well within the continental plate.

For the last 30 million years, plate tectonic forces

have slowly begun to tear the North American conti-nent apart along the Rio Grande rift. The lithospherehas been uplifted, stretched, thinned, broken, andintruded by magma. The resulting rift valley has slicedNew Mexico and half of Colorado in two for a dis-tance of over 600 miles. Near Taos the rift basin isabout 20 miles wide and approximately 16,000 feetdeep. The Rio Grande flows southward through suc-cessive rift basins that are linked by geologic constric-tions. The river itself did not excavate the rift; theriver follows the topographically lowest path along therift, from the San Juan Mountains in Colorado to theGulf of Mexico.

The transition from the basin to the surroundingmountains is abrupt, and in places such as near Taosand Pilar, is marked by steep slopes and cliffs. Theseabrupt transitions are both physiographic and geologicboundaries; most are major fault systems that delin-eate the margins of the rift. The eastern fault system isknown as the Sangre de Cristo fault. The southernfault (the Embudo fault) separates the San Luis andEspañola rift basins.

The rift basin is filled with young (less than 30 mil-lion years old) materials, principally of sediments shed

View northeast of the two principal elements of the Taos landscape: the Sangre de Cristo Mountains and the Taos Plateauand gorge. The gorge here contains Pleistocene landslides of the Pliocene Servilleta Basalt.


from the surrounding mountains, transported south-ward by the Rio Grande, and volcanic rocks of theTaos Plateau. We can see only the young basin fill atthe surface, although material as old as 5 million yearsis exposed in the bottom of the Rio Grande gorge. Thegorge is a much smaller and younger feature than therift, and it is entirely erosional. The river began cut-ting down into the plateau sometime after 2.8 millionyears ago, which makes it younger than the GrandCanyon in Arizona. The deepest section of the gorge,at 850 feet, is located west of Questa in the WildRivers Recreation Area.

Visible from the rim of the gorge is a series of near-horizontal layers of basalt, known as the ServilletaBasalt. Most of the basalt was erupted as long, thinflows from topographically low volcanoes near TresPiedras. The rift contains hundreds of such volcanoes,many of which are relatively young and retain theiroriginal conical shape. Nearly all of the isolated round-ed hills that are scattered across the Taos Plateau are

volcanoes that erupted from 6 to 2 million years ago. The rift basin is surrounded by alluvial fans that

have advanced from the mountains into the basin. Analluvial fan begins to form where a rapidly movingmountain stream flows out onto a relatively flat valleyfloor. As the stream suddenly loses velocity, the coars-

est sedimentary material is dropped by the stream.This material forms an “apron” that radiates out fromthe point where the mountain stream enters the valley.Most of this clay, sand, and gravel, called the Santa FeGroup, was eroded from the mountains during thepast 30 million years. Over time, as the basin subsidesalluvial fans are buried under successively youngeralluvium. The youngest of these alluvial fans sustainthe many sand and gravel quarries in the Taos Valley.

Many thousands of feet of rock were removed fromthe mountains and transported into the valley as themountains slowly pushed upward. Similarly, the RioGrande has deposited mineral-rich sediment into thebasin for millions of years. Much of the thick sedi-mentary material in the Santa Fe Group is porous andpermeable, and therefore serves as the principalaquifer in the region. People, agriculture, and industryhave tended to concentrate along the Rio Grande riftfor its fertile floodplain soils and precious supply ofwater.

Today, as uplift of the mountains and subsidence ofthe basin continue, streams persist in moving weath-ered rock from the mountains to the basin. The uplifttakes place episodically through a series of smallmovements, each one associated with an earthquake.Although these processes work so slowly that we seelittle if any change during our lifetimes, over geologictime the countless small changes translate into a never-ending cycle of magnificent landscapes that are succes-sively reduced to sand grains and washed to the sea.


Ute Mountain volcano rises above the basalt-capped TaosPlateau in northern Taos County. The Rio Grande excavat-ed the Rio Grande gorge during the last 600,000 years.

C H A P T E R O N E


12

The Sangre de Cristo Mountains occupy the easternhalf of the Taos region. Runoff from the steep

slopes of Precambrian-age igneous rocks andPaleozoic rocks, largely limestone, supplies significantquantities of high quality water to the Taos Valley,recharges the region's aquifers, and provides most ofthe water used in the region. This paper provides abrief summary of water supply and water use in theTaos region.

WATER SUPPLY

Water in streams and aquifers in the Taos region isimportant both locally and to downstream water usersalong the middle Rio Grande. In 2000 more than 92percent of all water diversions in Taos County (whichincludes surface and ground water diverted for alluses) originated from surface water sources, and morethan 97 percent of the region's domestic and publicsupplies originated from ground water. In short, sur-face water supports the region's agriculture and econ-omy, whereas ground water provides almost all of theregion's drinking water. The Taos region generates sig-nificant surface water resources through eleven peren-nial streams and rivers, which are important to localas well as downstream users, and stores large quanti-ties of ground water distributed in various local andregional-scale aquifers, some of which have beendeveloped. These two regional sources, surface waterand ground water, are intricately linked, and both dis-charge to the region's principal hydrologic feature, theRio Grande. The Rio Grande in Taos County is largelyunavailable for use because its course is in a deepgorge through much of the region, and because mostof its flow is committed downstream.

The entire Taos region is drained by the Rio Grande.The divide between the Rio Grande and CanadianRiver watersheds forms the county's eastern boundary.The Rio Grande brings an annual average of about325,500 acre-feet across the state line from Colorado,but almost all of the water used in the region is sup-plied by the tributaries, which also contribute to theRio Grande. The annual outflow from the region, asmeasured at the Embudo gage, averages 601,700 acre-

feet. Thus, the Taos region contributes an average276,200 acre-feet each year to the Rio Grande, whichis more than two-thirds of New Mexico's maximumannual allocation of water under the Rio Grande com-pact.

As the perennial streams of the Taos region exit thehigh crystalline-bedrock valleys of the Sangre deCristo Mountains and enter the lower alluvial valleys,a portion of their flow is generally lost to infiltrationthrough the coarse sand and gravel of alluvial fans andslopes. Although this loss diminishes the stream's dis-charge, it in turn replenishes storage in the region'saquifers and sustains shallow water levels in theregion's valleys. Mountain-front faults and low-perme-ability aquifer units can force shallow ground water tothe surface in some localities, producing springs,seeps, and marshes and rejuvenating stream flow. Thecomplex hydrogeologic conditions adjacent to themountain front give rise to complicated interactionsbetween water flow in streams and water flow inaquifers. As the region increases its reliance on groundwater, withdrawals from the shallow aquifers via wellswill eventually reduce stream flow by interceptingwater that would otherwise maintain the streams orby drawing water directly from the stream channels.

Precipitation in the region is strongly influenced byelevation. Average annual precipitation ranges fromless than 10 inches at Ojo Caliente (6,290 feet) tomore than 20 inches at Red River (8,680 feet).Monthly precipitation is generally greatest in July,August, and September. Runoff in the Rio Grandetributaries, on the other hand, reaches its peak inApril or May with melting of the accumulated wintersnow pack. Both precipitation and stream flow condi-tions are highly variable from year to year, and “aver-age” conditions are the exception rather than the rule.In general, historic stream flow fluctuates betweenperiods of above-normal and below-normal discharge,separated by short periods of transition. The mostsevere dry conditions occurred between 1950 and1964, when annual discharge for this fifteen-year peri-od averaged only 341,000 acre-feet or 57 percent ofnormal. The wettest period on record occurred duringthe strong El Niño events of the mid-1980s, which

Hydrology and Water Supply in theTaos Region

John W. Shomaker, John Shomaker & Associates, Inc.Peggy Johnson, New Mexico Bureau of Geology and Mineral Resources

produced a five-year average flow that was 180 per-cent of normal. (Given the precipitation records todate for this year, 2005 may become the wettest yearon record.

WATER USE

Apart from small diversions and shallow wells in thenarrow higher-elevation valleys, the region's water usetakes place in the lower valleys adjacent to its perenni-al streams and along the east side of the Rio Grande

Generalized geologic map of Taos County.

gorge. About 99,557 acre-feet (97.9percent of it surface water) wasdiverted for irrigation in the Taosregion in year 2000, which in turnaccounted for 92.7 percent of allthe water withdrawn. Sixty-one per-cent (60,289 acre-feet) of the waterdiverted for irrigation was returnedto streams. Water use for mining inyear 2000 was 3,094 acre-feet,about 2,568 acre-feet of which (83percent of the water diverted formining) became return flow, avail-able to other users. Overall, 60 per-cent of the water diverted for use inTaos County is returned to thestreams and aquifers and remainsavailable for other users.

Some 2,255 acre-feet, almost allfrom ground water, was withdrawnfor public supply in 2000, andanother 1,376 acre-feet waspumped from domestic wells.Ground water pumping for publicand domestic supply roughly dou-bled in the fifteen years between1985 and 2000. The largest user isthe town of Taos, pumping roughlyone-third of the public supply; theremainder is produced by the ElPrado Water and Sanitation Districtand many small mutual-domesticsystems. About 59 percent of thewater pumped for public supplywas returned to streams as treatedwastewater; virtually all of the waterfrom domestic wells is assumed to

have been lost to evaporation.

WATERSHEDS

The perennial streams and rivers within the Taosregion occupy large to intermediate drainage basins onthe western face of the Sangre de Cristo Mountains.The principal watersheds in the region are summa-rized here:

Taos Valley

The Taos Valley includes two major drainages, ArroyoHondo and the Rio Pueblo de Taos. The Rio Pueblo is



C H A P T E R O N E


14

sustained by five major tributaries: Arroyo Seco, RioLucero, Rio Fernando de Taos, Rio Grande delRancho, and Rio Chiquito. The combined drainagearea of these streams is about 530 square miles. Muchof the discharge in these streams is diverted for irriga-tion in summer, but a combination of return flowfrom irrigation and winter flows provides recharge to acomplex aquifer system and augments flow in the RioGrande.

The water table is at land surface in much of theeastern part of the valley, creating Taos Pueblo'sBuffalo Pasture and other marsh areas and supportinginnumerable small seeps and springs. These occurwhere the highly permeable, shallow aquifer thins,loses storage capacity, and is unable to transmit thefull amount of the recharge entering the aquifer alongthe foot of the eastern mountains. The water table hasdeclined in recent years, partly in response to droughtand presumably also due to increased ground waterpumping. The surface area of the Buffalo Pasture issaid to have decreased, some springs have stoppedflowing, and many shallow wells have failed.

Recharge moves westward away from the mountainfront, and downward through a sequence of basaltflows and interbedded sediments close to the surface,then through sandstone, mudstone, and conglomerate

beds of the Tertiary-age Santa Fe Group aquifer beforedischarging into the Rio Grande. The Rio Grandegorge at the western edge of the Taos Valley is500–600 feet deep, and the 700–900-foot elevationdifference between the areas of recharge and the RioGrande, over the relatively short distance of 7–9 milesbetween the river and the mountain front, leads to astrong downward component of ground water flow,and probably to perched ground water and unsaturat-ed conditions below the water table in many places.Recharge to the Taos Valley aquifer system probablyaverages about 37,500 acre-feet per year, a third ofwhich is in the form of seepage from irrigation. About15,000 acre-feet per year, or 21 cubic feet per second,discharges to the Rio Grande through seeps andsprings, and flow through the channel bottom,between the mouth of Arroyo Hondo and the TaosJunction gage.

Pumping tests of wells indicate ranges in flow froma few tenths of a foot per day to 22 feet per day forthe alluvium, from about 5 feet to more than 25 feetper day for the underlying Tertiary-age basalt andassociated sediments, and from a few tenths of a footto about 2 feet per day for the still deeper Tertiary-ageTesuque Formation beds in the basin fill. Well-yieldsvary from place to place, but pumping rates as high as

Geologic cross section showing approximate location of the watertable in the Taos region. Recharge from the mountains infiltratesand moves westward toward the Rio Grande. Ground water flowis influenced by the geologic materials in the subsurface and by

geologic structures, such as faults. Colors correspond to the geo-logic map on the inside back cover. Note that the vertical scale isexaggerated in order to show topography. Courtesy of Paul Bauer,from unpublished data.

several hundred gallons per minute have been report-ed for wells tapping the relatively shallow alluvium.Rates for wells in the underlying basalt and associatedsediments have been as high as 120 gallons perminute and, for the still deeper beds, as high as 500gallons per minute.

Pumping from wells affects the flows in the streamsnear the mountain front. Because of the strong down-ward flow and potential for some disconnect betweenshallow and deep ground water, it is likely that futurewells will be deep, cased through the upper part ofthe aquifer, and preferentially located near the RioGrande, in order to minimize both the effects on thestreams and drawdown in the many shallow wells.Wells are commonly less than 200 feet deep in theeastern part of the valley, but must be more than 800feet deep near the Rio Grande to penetrate below thewater table. There are an estimated 1,900 privatedomestic wells in the Taos Valley.

The combined average yield of the Taos Valleystreams is estimated at about 94,000 acre-feet peryear, varying from about 80 percent of that (or 76,000acre-feet per year) in “dry” years to 138 percent ofthat (or 129,000 acre-feet per year) in “wet” years.(Dry and wet years are defined by the 25th and 75thpercentile, respectively, of flow in Arroyo Hondo andthe Rio Pueblo de Taos.) Ditches on Taos Pueblo landsplus some fifty-five acequias on non-pueblo lands irri-gate about 14,000 acres along the eastern side of thevalley. Although the average annual flows of thestreams that serve these ditches and acequias are theo-retically sufficient to supply them, the variability fromyear to year, and the concentration of flows during thespring and early summer, lead to shortages during lateirrigation season in most years. There is no reservoirstorage on most streams.

Sunshine Valley

The Sunshine Valley is a high plain lying between theSangre de Cristo Mountains and the Rio Grande, andbetween Questa and the Colorado state line. Shallowground water pumped from alluvium, Santa Fe Groupbasin fill, and interbedded basalts irrigates about 600acres (year 2000). There are no perennial streams.Recharge to the Sunshine Valley aquifer has been esti-mated at 20,000 acre-feet per year. If there were noground water pumping, this amount would dischargefrom the aquifer system to the Rio Grande. Well yieldsin the Sunshine Valley are generally as high as 1,200gallons per minute, but a 3,000-gallons-per-minute

well has been reported. The high permeability of thealluvium and basalts, which accounts for the highyields, also leads to large depletion of flow in the RioGrande as a result of pumping.

Costilla Creek Valley

Costilla Creek drains the northern Sangre de CristoMountains, yielding an estimated average of about29,000 acre-feet per year. Costilla Reservoir, at almost9,500 feet in elevation and with a nominal capacity of16,500 acre-feet, regulates deliveries. Eighteen ace-quias serve about 5,500 acres of irrigation, and alsodeliver water to irrigators in Colorado and theSunshine Valley. Ground water use is limited todomestic and livestock supplies, and about 100 acresof irrigation.

Red River Valley

The Red River watershed yields an estimated averageof about 50,400 acre-feet per year. The thin, narrowbody of alluvium in the bottom of the valley and frac-tured bedrock close to the river are sufficiently perme-able to support relatively high yield wells, but theirproduction is, in effect, diversion from the river.About 3,100 acres are under irrigation from the RedRiver and its tributary Cabresto Creek. The Molycorpoperations above Questa represent the only other largediversion. The town of Red River diverted about 87acre-feet of surface water in 2000 and pumped about487 acre-feet of ground water for public supply.

This summary is based on published reports, but waterrights in the Taos Valley are in the process of adjudication,and much new work, confidential as of this writing, hasbeen done to refine the inventory of irrigated acreage, theunderstanding of the flows in streams and the groundwater system, and the expected pattern of future wateruse.

Suggested Reading

Drakos, P., Lazarus, J., White, B., Banet, C., Hodgins, M., Riesterer, J, andSandoval, J., 2004, Hydrologic characteristics of basin-fill aquifers in thesouthern San Luis Basin, New Mexico; in Brister, B. S., Bauer, P. W.,Read, A. S., and Lueth, V. W. (eds), Geology of the Taos region: NewMexico Geological Society, Guidebook 55.

Garrabrant, L. A., 1993, Water resources of Taos County, New Mexico:U.S. Geological Survey, Water Resources Investigations Report 93-4107.



C H A P T E R O N E


16

The agricultural tradition in the Taos Valley beganhundreds of years ago with Pueblo culture,

expanded with Spanish settlement, and continuestoday as an important economic foundation for ruralcommunities in the valley. Irrigated agriculture is sus-tained in Taos, and throughout much of the RioGrande valley, by stream flow originating in theSangre de Cristo and Picuris Mountains east andsouth of the Taos Valley. The ancient and historic set-tlement patterns that created the present-day popula-tion centers surrounding Taos Pueblo, Taos, El Prado,Ranchos de Taos, Ranchitos, Cañón, and ArroyoHondo among others, were determined by the abun-dance of fertile land and irrigation waters surroundingthe valley's major streams.

Although irrigation in the Taos Valley is typicallyassociated with the Spanish acequia culture, the prac-tice of irrigated agriculture was initiated by Pueblofarmers long before Spanish settlement. When theSpanish first arrived in the Taos Valley in 1540, theywere notably impressed by the stature of Taos Pueblo.Narratives of the Coronado expeditions noted that allpueblos, including Taos, grew maize, beans, andsquash, and observed that the Rio del Pueblo (RioPueblo de Taos) that divided the village flowed swiftand deep. When Spanish settlers returned to the RioGrande in 1598, Juan de Oñate admiringly describedPueblo agriculture to the Spanish king and viceroy,noting that the Pueblo Indians were skilled farmers.Some fields were irrigated, and others relied on sum-mer rains. The region later proved particularly welladapted for irrigated wheat production, and bumpercrops grown with a dependable water supply madethe region New Mexico's breadbasket when shortagesthreatened elsewhere. Today 92 percent of TaosCounty's water requirements (107,342 acre-feet) aresupplied by surface water, most of which is used forirrigated agriculture.

The issues of population growth, water demand,and over-allocation that dominate today's headlinesand planning agendas first emerged with Spanish col-onization on land surrounding Taos Pueblo. Duringthe turbulent years before the Pueblo Revolt of 1680,early Spanish occupants settled along the rivers northand west of the pueblo to take advantage of the fertile

lands and abundant water for irrigation. Post-revoltresettlement in the Taos Valley renewed requests foragricultural and grazing lands situated along the val-ley's major streams, resulting in land grants through-out the valley by the Spanish government. One of theearliest references to a specific acequia in the Taos area(September 1715) cites the Acequia de los Lovatos,the eastern boundary of the Gijosa Grant, which origi-nates in the Rio Pueblo and is still in use today.Modern records document approximately eighty ace-quias and ditches operating in the Taos Valley, most ofwhich date from Spanish development in the eigh-teenth and nineteenth centuries.

Early settlers and provincial officials knew that nocommunity could exist without an assured water sup-ply. As early as 1795, accelerating population growthcaused increased competition between Hispanos andPueblo Indians for water, and the early New Mexicanwater administrators (cabildos or ayuntamientos) devel-oped various methods to adjust land policy with wateravailability in a semiarid environment. Hence beganthe practice of water administration that still embroilsthe region today.

From the earliest Spanish chronicles of waterresources to the recent state engineer assessments inthe late twentieth century, observers have noted,quantified, and apportioned the prodigious but highly

A History of Agricultural WaterDevelopment in the Taos Valley

Peggy Johnson, New Mexico Bureau of Geology and Mineral Resources

Distribution of water use in Taos County today.

variable flows in the major streams of the Taos Valley,which include the Rio Hondo, Rio Lucero, Rio Pueblode Taos, Rio Fernando, and Rio Grande del Rancho.The Red River, which occupies a major watershednorth of Arroyo Hondo, drains the area developed bythe Molycorp molybdenum mine and provides water

for irrigation and domestic use forthe community of Questa. Thesesix streams and their watershedsprovide much of the water thatsustains the Rio Grande on itscourse through New Mexico.

RIO PUEBLO DE TAOS AND RIOFERNANDO

The Rio Pueblo drains an area of67 square miles in the Sangre deCristo Mountains and produces anaverage annual discharge ofapproximately 22,000 acre-feet.Waters from the Rio Pueblo havebeen used by residents of TaosPueblo for untold years beforeSpanish settlement, but the earliestwritten descriptions of the valleywere made by Franciscan friarsduring visits to New Mexican mis-sions. These early reports alwaysnoted the “fair-sized rivers” andthe fields of wheat and corn culti-vated by Taos Indians and irrigatedfrom the Rios Lucero and Pueblo.The earliest Spanish settlementalong the Rio Pueblo began down-stream of Taos Pueblo with author-ization of the Gijosa Grant onSeptember 20, 1715. A populationexplosion during the 1790s causedincreased competition for land andwater between settlers and thepueblo and among the settlersthemselves. A census in 1796 con-firmed a Pueblo Indian populationof 510 at Taos and 199 at Picuris,approximately one-half of thearea's total population. TheHispano population had grownfrom 330 to 779 since the last cen-sus in 1790, a 135 percent

increase in six years. The census indicated about tenfamilies at each of the villages within the Gijosa Grantalong the Rio Pueblo now known as Upper and LowerRanchitos.

Despite being the smallest of the principal tributar-ies feeding the Rio Pueblo de Taos, the Rio Fernandoirrigates many acres of crops and pasture. Dependenton springs and snowmelt, the Rio Fernando drains 70

Drainage basins and streams in Taos County.



C H A P T E R O N E


18

square miles below Palo Flechado Pass in the Sangrede Cristo Mountains, with a mean annual discharge of4,140 acre-feet. Authorized Hispano settlement beganin 1796 with the Don Fernando de Taos Grant, whichencompassed lands adjacent to Taos Pueblo andbisected by the Rio Fernando. With sixty families tak-ing residence in the first year, followed by a numberof new arrivals a year later, the Fernando Grant quick-ly became the largest Hispano community in the val-ley. In the fall of 1797, after only two planting sea-sons, a request was made by the new residents forrights to the surplus waters (sobrantes) from the RioPueblo and Rio Lucero, suggesting that the RioFernando had already proved inadequate for the set-tlers' needs. A sobrante right meant that the newcom-ers at Don Fernando could use any water remainingafter Pueblo farmers had satisfied their requirements.For many years Hispano farmers managed to maintaingood relations with the pueblo, and irrigators foundways to share the stream's water without resorting tolawsuits. In 1871, however, litigation changed the set-tlers' sobrante right into an absolute share, thus initi-ating an era of repeated controversies over apportion-ment between the pueblo and downstream users. TheAbeyta adjudication represents the current apportion-ment suit.

An unusual water management case, possibly the firstwith environmental implications, occurred on the RioFernando in the spring of 1877. Several landownerswho depended on the Rio Fernando for irrigation watercomplained that a certain Juan Sánchez had been sys-tematically cutting down large numbers of cottonwoodtrees near the river's headwaters, thus eliminating thecooling shade that protected the stream. Exposure tothe blazing sun, they claimed, would cause water short-ages from evaporation. The presiding judge ruled infavor of the plaintiffs, finding that excessive timber cut-ting in the bosque would lead, little by little, to diminu-tion of the water necessary for agriculture in the valley.Thereafter, anyone convicted of such destruction wouldbe regarded as a transgressor, subject to all the rigors ofthe law. Although nineteenth century New Mexicansappeared generally unaware of environmental issues,this case demonstrates an intuitive understanding of thebasic concepts of a hydrologic cycle and water balanceapplied by present-day hydrologists.

RIO GRANDE DEL RANCHO

The Rio Grande del Rancho, with tributaries the RioChiquito, the Rito de la Olla, and Arroyo Miranda,drains the south side of the Fernando Mountains and

the north side of the Picuris Mountains. This fairlylarge watershed (150 square miles) is mostly coinci-dent with the Rio Grande del Rancho Land Grantauthorized in 1795 and includes the towns of Talpaand Llano Quemado. Diversion of stream flow belowTalpa through nineteen acequias and ditches currentlyprovides irrigation for more than 3,380 acres. Astream gage located on the Rio Grande del Ranchonear Talpa has operated since 1953, recording a meanannual discharge of 15,340 acre-feet.

The oldest Spanish grant in Taos Valley, authorizedon June 15, 1715, to Captain Cristóbal de la Serna,allocated a tract of agricultural and grazing land westof the Rio de las Trampas (Rio Grande del Rancho)near present Ranchos de Taos. The Serna Grant waslater sold to Diego “El Coyote” Romero, developedsuccessfully, and passed to his heirs. One of the earli-est conflicts concerning water and land allocationoccurred along the Rio Grande del Rancho whenRanchos residents protested upstream settlement byoutsiders on the proposed Rio Grande del RanchoGrant early in 1795. Additional irrigation above theirfields, they said, would inevitably diminish their shareof the river's flow and endanger the livelihood of pres-ent landowners (and added that decreased harvestsmeant a corresponding decline in tithes and first fruitsnecessary for maintenance of the church). In an effortto thwart upstream settlement, the protestors peti-tioned the governor, asking that they themselvesreceive possession of the grant lands. The request wasapproved on February 4, 1795, thus consolidatingcontrol of the river's headwaters into the hands of theRanchos residents.

THE RIO LUCERO AND ARROYO SECO

Arroyo Seco and the Rio Lucero begin in adjoiningcanyons south of the Rio Hondo and run southwestfrom sources high in the Sangre de Cristo Mountainsto meet the Rio Pueblo near Los Cordovas and UpperRanchitos. Settlement between the Lucero and theHondo began before the Pueblo Revolt of 1680 andcontinued through the eighteenth century in a bewil-dering series of overlapping grants, including AntonioMartínez in 1716, Pedro Vigil de Santillanes in 1742,and Antonio Martín in 1745. Actual colonization atArroyo Seco and Desmontes was delayed until theearly nineteenth century, when the land betweenArroyo Seco and Arroyo Hondo came under the con-trol of Mariano Sanches, an aggressive land developer,who began a vigorous campaign to colonize thebrush-covered flats. In a plan involving exchange of

from the Rio Lucero and runs it for more than a mileacross the dry plain to Arroyo Seco Creek, where itfollows the channel downstream for later diversion orcrosses the creek for distribution through a network ofsmaller ditches totaling several miles in length. Themain canal, La Acequia de la Cuchilla, represents aneven greater task. Diverting water from the Rio Hondoabove present Valdez, the Cuchilla climbs up thesouth wall of Hondo Canyon for more than two milesbefore reaching the plain at the top, where it dividesinto several laterals that water fields at Desmontes.The ditch, which seems to run uphill, is still regarded

land for services, the entrepreneur offered potentialfarm sites to workmen (trabajantes) enlisted to clear(desmontar) the plain's thick growth of sage, piñón,and juniper. Named by the brush cutters, Desmontesgrew up as a scattered settlement on the high, dryplains north and west of the Arroyo Seco. Not surpris-ingly, Arroyo Seco provided only a bare minimum ofwater for irrigation, causing the trabajantes to cooper-ate in the construction of two major canals that divertwaters from other streams. Each one represents a for-midable project; both are still in use. The AcequiaMadre del Rio Lucero del Arroyo Seco diverts water

Modern efforts to measure dis-charge from the region's streams

rely on a series of stream gages ormeasurement stations installed andadministered by the U.S. GeologicalSurvey (USGS) and the New MexicoOffice of the State Engineer andInterstate Stream Commission. Theoldest such station in the UnitedStates, active since 1890, is located onthe main stem of the Rio Grande atEmbudo station. In March of 1888,responding to a sudden interest inwestern irrigation, Congress passed ajoint resolution authorizing theSecretary of the Interior to examinepotential irrigated lands, locate possi-ble sites for water storage, and deter-mine the capacity of various streams.Responsibility for the project fell toJohn Wesley Powell, then serving asdirector of the U.S. Geological Survey.

Recognizing a shortage of personneltrained in water measurement, Powellordered the establishment of a schoolfor hydrographers on a western river.The Rio Grande near Embudo stationwas selected because of its location inan arid region on a major streamunlikely to freeze in winter. For fivemonths between December 1888 andApril 1889, eight recent graduatesfrom prestigious eastern engineeringschools worked under FrederickHaynes Newell to learn a technique ofwater measurement known as streamgaging. The class made regular meas-urements of water temperature, depth,and velocity in the Rio Grande atEmbudo station from a makeshift raft,thus providing the first such measure-ments recorded in the United States.

Historically, thirty-five such stationshave operated between the NewMexico–Colorado state line andEmbudo, although only twenty-oneare currently active. These gages meas-ure stream discharge (in units of cubicfeet per second or cfs) on an hourlybasis. Real-time data reflecting currentconditions are recorded at 15 to 60minute intervals, stored on site, andthen transmitted to USGS offices everyfour hours. Recording and transmis-sion times may be more frequent dur-ing critical events. Data from real-timesites are relayed via satellite, tele-

phone, or radio and are available forviewing within three minutes ofarrival. Online data for Embudo sta-tion can be found athttp://nwis.waterdata.usgs.gov/nwis/nwisman/?site_no=08279500&agency_cd=USGS.

What began at the Embudo gage in1889 developed into a programencompassing approximately 1.5 mil-lion sites in all fifty states, the Districtof Columbia, and Puerto Rico. Thisnetwork of stream gage stations pro-vides a critical dataset that allowsmonitoring during critical floodevents, supports a statistical assess-ment of the amount of water availablefor diversion and use, and facilitateswater management and administrativedecisions.

The Embudo Gage and Stream Flow Measurement in Taos County

These geologists measuring flow onthe Arkansas River in Colorado ca.1890 are using procedures developedat Embudo.

Embudo gage today.




New Mexico became a territory, citizens turned to thenewly established court system to resolve water dis-putes. On May 19, 1852, Arroyo Hondo againbrought suit in probate court against the inhabitantsof Desmontes to determine rights of the two commu-nities to water from the Rio Hondo. The presidingjudge ruled that Arroyo Hondo had first priority, butallowed Desmontes one-third of the river’s flow, evenin time of scarcity. According to local residents thisapportionment is still observed by the mayordomos ofthe acequias involved, with Arroyo Hondo’s two-thirdsdivided between its own users and those of Valdezand Cañoncito.

Suggested Reading

Historic notes regarding Pueblo and Spanish agricultureand water development and early New Mexican wateradministration are taken from the two works of Baxterlisted below. Information on water availability in theregion's major streams is from the two Johnson referenceslisted.

Baxter, John O., 1990, Spanish irrigation in Taos Valley. New Mexico StateEngineer Office, Santa Fe, NM, 126 pp.

Baxter, John O., 1997, Dividing New Mexico's waters, 1700-1912.University of New Mexico Press, Albuquerque, NM, 135 pp.

Johnson, Peggy, 1998, Surface-water assessment, Taos County, NewMexico. New Mexico Bureau of Geology & Mineral Resources Open-File Report 440.

Johnson, Peggy, 1999, Availability and variability of surface-waterresources in Taos County, New Mexico - an assessment for regionalplanning. New Mexico Geology, vol. 21, no. 1, February 1999.

Five year moving average of annual discharge for the RioGrande at Embudo, compared to mean annual precipita-tion for Cerro, Red River, and Taos.

with awe by professional engineers. However, ArroyoSeco’s claims to water from two other rivers causedrecurrent disputes with Arroyo Hondo, Taos Pueblo,and Fernando de Taos.

RIO HONDO

From its source among the high peaks of the Sangrede Cristo Mountains, the Rio Hondo rushes westwardpast the villages of Valdez and Arroyo Hondo beforejoining the Rio Grande 14 miles northwest of Taos.With an average annual discharge of more than25,000 acre-feet, the river irrigates 3,700 acresthrough fifteen acequias. Official colonization in theHondo Valley began in 1815 with authorization of theArroyo Hondo Grant. Settlers along the Rio Hondolived in harmony with their southern neighbors onthe plain until the founding of San Antonio (today’sValdez) in 1823. While certifying Arroyo Hondo Grantpapers in 1823, Alcalde Juan Antonio Lovato addedlanguage to the grant records in order to resolve thewater dispute with Arroyo Seco. Lovato made theright of Arroyo Hondo village superior to that of SanAntonio, and put both ahead of Arroyo Seco andDesmontes. Desperate for irrigation water, residents ofthe southern plain persuaded Arroyo Hondo to allowthem a substantial part of the flow from their stream,a practice that became a matter of local custom. After

The Rio Hondo in the Wheeler Peak area.




Mighty mountains, sparkling streams, valleys fair tolook upon, set like precious stones in a region whichcombines the lovely and the lofty, the bold and thebeautiful, the placid and the picturesque—this is thenew El Dorado of Red River, Taos county, northernNew Mexico…. –Anon 1897

The mineral riches and grandeur of Taos Countythat moved this unknown scribe to wax so elo-

quently have weighed heavily on the human imagi-nation since prehistoric times, beginning in earnestsoon after the arrival of the Spanish in 1540.However, various factors limited the development ofits resources on a large scale well into the twentiethcentury. Remoteness and elevation were major adver-sities, then and now. The infrastructure usually asso-ciated with heavy industry, such as main and branchline railroads and factories, was totally lacking orlong in coming. Moreover, the high country, one ofthe county's many endearing attractions, has alwaysbeen difficult to access.

Native Americans took advantage of the mineralsubstances indigenous to the area for uses that theydeemed necessary to their everyday lives: clay andmica for the manufacture of pottery, the various sili-ca minerals for fashioning tools, knives, andweaponry, and certain colorful minerals for use inpersonal adornment and pigmentation. Historicallyspeaking, gold placers, particularly at Arroyo Hondo,as well as other mines and prospects in the“Embuda” and Picuris areas, were said to have beenworked by the Spanish long before the PuebloRevolt in 1680. American miners often encounteredevidence of their Spanish predecessors. Garnet“mines” were reported in the Picuris area around1627 by Father Salmeron, and the ex-governor ofPicuris Pueblo escaped the rather serious charge ofwitchcraft by disclosing the location of four veins ofsilver in Picuris Canyon in 1713. Prospectors duringthe Mexican period (1821–1848) worked the placersnear what would become Amizette during the 1820sand 30s.

Taos County's many contributions to mineral dis-coveries and developments elsewhere in the Old

West are also of significance. Many of the legendarypioneer trailblazers such as Kit Carson, LucienMaxwell, and others were involved with mining andprospecting in Taos County and environs. Taos minerJ. P. L. Leese arrived in California in 1833 or 34 with aconsiderable quantity of gold dust—gold that likelyoriginated from the Arroyo Hondo placers, the smallproduct of which had long been traded in Taos com-merce and became part of the first gold shipment outof California.

Taos County’s Mineral Heritage—A Unique Page in New Mexico’s Mining History

Robert W. Eveleth, New Mexico Bureau of Geology and Mineral Resources

The Taos Mining Company (a successor to the Fraser MountainCopper Company) was without doubt the most elaborate andcostly attempt to develop the elusive metal deposits in the RedRiver district before 1920. The mill and smelter at the base ofFrazer Mountain are pictured along with company officialsClarence Probert, James Sparks, John Bidwell, and WilliamHarper. [Author's collection.]


The instrument that opened the floodgates to thevast American West, including New Mexico west ofthe Rio Grande, was the 1848 Treaty of GuadalupeHidalgo, which transferred ownership of much ofArizona and New Mexico from Mexico to the U.S. Thenew American proprietors immediately assumed theresponsibility of dealing with the Apaches,Comanches, and others; they spent the next half-cen-tury engaging in military action to pacify the region.The American military provided some of the earliestaccounts of rich mines and mineral resources. Theearly American press obligingly waxed eloquently onthe existence of rich mines in the Taos area and else-where in the new territory and fired the imaginationsof American prospectors. But the greatest influx ofprospectors came with the close of the American CivilWar.

MT. BALDY TO THE TAOS RANGE

Fort Union, near present day Watrous in MoraCounty, was the principal supply depot for the mili-tary infrastructure in New Mexico Territory and was ofparamount importance in protecting travelers and the

pioneer merchants along the Santa Fe Trail. All repre-sentatives of Old West society ventured to this out-post, including Native Americans who regularly trad-ed with the prospectors stationed there. In 1866 a Utestopped by with some high-grade copper specimensto barter for supplies and was directed to WilliamKroenig and others of the prospecting fraternity.Recognizing the potential value, the group either trad-ed or paid the Indian for the specimens and, as part ofthe deal, were escorted to the locality near the top ofMount Baldy (near Elizabethtown) where they locatedthe famous “Mystic Copper Mine.” Additionalprospecting soon revealed the presence of placer goldon Ponil Creek, and the rush was on. Elizabethtownwas soon established; from there the miners fannedout to the west toward Taos and scrutinized the majordrainages and peaks in search of more treasure. Thefew prospectors in the Taos area were doing much thesame in reverse by tracing the placers eastward totheir sources. Many promising discoveries followed,and miners were soon working the ground at ArroyoHondo and Red River. During the next two decadeslocalities such as Black Copper, Keystone, Anchor,Midnight, LaBelle, Gold Hill, Twining, and Amizetteexperienced the touch of the pick, shovel, pan, andsluice.

The arrival of the railroads in the 1880s broughtimmediate attention and development to NewMexico's vast coal resources: Magdalena's lead, silver,


The Denver & Rio Grande Western Railroad pushed its nar-row-gage tracks south from Antonito along the westernflanks of the Rio Grande through such garden spots as NoAgua, Tres Piedras, and Embudo, thereby forever bypassingthe more populous Taos. Thus Tres Piedras (shown here inthis ca. 1910 view) and Embudo were Taos county's solerailroad shipping points. Had the railroad survived beyond1941, it doubtless would have thrived on the No Agua per-lite traffic. The long abandoned Tres Piedras water tank stillstands today.

The Independence mine on Bitter Creek, Red River, ca.1905.

and zinc deposits, and southwestern New Mexico'sbase and precious metal districts. For a time TaosCounty was left far behind in the developmentalscheme of things. The Denver & Rio Grande WesternRailroad constructed its right of way down the westbank of the Rio Grande (thereby avoiding a very cost-ly bridge across the gorge but forever bypassing Taos)through such thriving burgs as No Agua, Tres Piedras,and Embudo, on its way to a terminus in the EspañolaValley, the only real population center along the line.The inevitable talk of a branch line railroad was revis-ited as each little mining camp experienced its fleetingmoment in the sun. The railroads wisely assumed a“wait and see” stance, with the result that Tres Piedras,Taos Junction, and Embudo were, through September1941, the only real railroad shipping points TaosCounty ever had.

LATE NINETEENTH / EARLY TWENTIETH CENTURYMINING VENTURES

Despite nearly a century of prospecting, exploration,and sometimes extraordinary developmental effort,few if any mines and prospects in Taos County couldbe considered successful before 1920. Small zones of

high-grade precious metal-bearing ores were occasion-ally encountered, which only further served toencourage the miners to pursue the inconsistent andelusive deposits so typically hosted by thePrecambrian and Tertiary rocks in the Taos Countyarea. Notably rich but woefully small pockets of goldore were discovered in such mines as the Memphisand Independence (both on Bitter Creek). These dis-coveries too often resulted in premature, ill-advisedinvestments in elaborate milling and, at least in onecase, smelting facilities at properties such as theCaribel Group on Pioneer Creek, the Buffalo–NewMexico property on Placer Creek, the ChampionCopper Company on Copper Hill, the Fraser (sic)Mountain Copper Company mine at Twining, andmany others.

Sketch map of surface improvements at the Champion CopperCompany property on Copper Hill, Picuris district, from the1917 annual report. Most of the improvements should havebeen postponed pending the development of economicallyminable ore.

Arthur Montgomery and crew sorting beryl ore at theHarding pegmatite mine, Taos County, New Mexico, ca.1952. The Harding was at times the nation's leading producerof beryl and the rare-earth minerals columbite-tantalite andmicrolite.





nation of the crystals and rhombs, declared them “tobe the finest in quality and the largest in size everknown.” The mine is now a priceless mineralogicaland geological “laboratory” administered by theUniversity of New Mexico, a gift of the late ArthurMontgomery.

The yellowish outcroppings near Questa, originallythought to be sulfur, turned out to be ferrimolybditeand were an indication of a subsurface molybdenumsulfide deposit. The Molybdenum Corporation ofAmerica acquired the property from its early ownersin 1920 and has since produced molybdenum sulfidemore or less continuously. The mine has gone throughthree distinct phases beginning with traditional under-ground methods focusing on the narrow, high-gradeveins, then evolving into open-pit mining in 1965,and finally back to large-scale underground mining oflower-grade material in 1983. Milling at Questa hassimilarly gone through many technological changesand improvements since the early days. Questa istruly a world-class deposit, having produced about aquarter billion pounds of molybdenum sulfide to date.

The value of perlite went unrecognized until the late1940s. Within a few short years of initial testing andresearch, perlite was found to be invaluable for awhole host of end uses including lightweight aggre-gates, abrasives, potting soil additive, filtering media,insulation, absorbents, and many others. The No Aguaperlite deposit a few miles north of Tres Piedras, cur-rently recognized as the world's largest, gave TaosCounty its second so-called “world-class” deposit. F. E.Schundler built the first mill in the district and beganproduction in 1951. Johns Manville took over theproperty in 1959, and since then several other compa-nies and/or successors have been active in the district.

Mica, unlike perlite, has a long history of exploita-tion in New Mexico but was of little economic impor-tance until recently. One of the largest recently mineddeposits of mica (sericite) in the United Stated is atthe U.S. Hill mine (aka Tojo) in southeastern TaosCounty, once owned and operated by the cleverlynamed “Mineral Industrial Commodities of America,Inc.” (M. I. C. A.) and most recently by OglebayNorton. The ore is mined by standard mechanicalstripping techniques, screened, and then trucked tothe company's grinding and flotation mill on the RioGrande near Velarde. Reserves are sufficient fordecades of operations, but the future of the mine is indoubt due to very strong resistance of the local popu-lace over environmental and cultural concerns (thelocal pueblos use the mica in their pottery).

Even with the extravagant efforts of the FraserMountain Copper Company (and its successor, theTaos Mining Company) and others, the mineral pro-duction record for Taos County before 1923 wasapproximately $100,000—a mere trifle of the amountinvested. The small production of gold dust won bythe pioneer miners went largely unrecorded, butregardless of all the hype, hope, and eternal optimismexpressed by such camps as Amizette, LaBelle, BlackCopper, and others, officially credited production is ator near zero. Events in the twentieth century wouldquickly change all that, and Taos County would final-ly enter the ranks of world-class mineral producers.

ALL THAT GLITTERS IS NOT GOLD (SOME OF IT ISMICA)

Taos County is unique among New Mexico's mineralproducers for commodities such as beryl, columbite-tantalite, microlite, and one of the world's largestdeposits of optical calcite at the Harding mine; mica(sericite) at the U.S. Hill (Tojo) mine; and molybde-num at Questa. Add to that the No Agua perlite, andthe value of Taos County's mineral production since1923 (exclusive of sand, gravel, and crushed stoneproducts) approaches a half billion dollars.

The Harding pegmatite, located as early as 1900,went largely unappreciated until a miner from theBlack Hills recognized in 1919 the true identity of themineralogical suite. The lithium-bearing minerals werefound to be of value in the manufacture of glass (andEdison's alkaline storage batteries), and a new indus-try was born. The Embudo Milling Company erecteda grinding plant at Embudo station on the Denver &Rio Grande Western Railroad and shipped over10,000 tons of lithium-bearing concentrates beforesuddenly ceasing operations in 1930—due, it is said,to the contamination by some “troublesome” tantalummineral. The mine ultimately proved to be a veritabletreasure trove of rare and unusual minerals (includingthat very same troublesome columbite-tantalite andmicrolite, beryl and optical-quality calcite. TheHarding pegmatite yielded the lion's share of thenation's tantalum supply—over 20,000 pounds ofmicrolite and columbite-tantalite concentrates duringWorld War II—and at times was the nation's leadingproducer of beryl. The nearby Iceberg calcite deposit,the second largest ever discovered in the world, pro-duced well over 1,000 pounds of optical-quality mate-rial, much of it sold to Bausch & Lomb OpticalCompany. The U.S. Bureau of Standards, upon exami-

MINING LAWS, THE ENVIRONMENT, AND THEFUTURE

Attitudes and opinions of society have changed radi-cally. Well into the middle of the twentieth centuryAmericans often perceived their local mining activitywith a sense of pride. Despite the tradeoffs, such asmine dumps and sometimes malodorous mills, theywere keenly aware of the economic benefits. This isthe two-edged sword of our mining legacy: Thebenign side is represented by the vast amounts ofwealth and useful materials won from the earth. Thenegative side is represented by the non-essentialbyproducts derived from those commodities: tailingsdams, slag piles, and other wastes left over from pastoperations.

What has changed most, however, is the world'spopulation, and that has spawned a staggeringdemand for the mineral feedstocks of civilization. Themining industry has responded by conducting opera-tions on a much larger and more efficient scale.Where the pick, shovel, sluice, pan, and single-horse-power haulage once prevailed, miners of today takeadvantage of motorized trucks capable of hauling ahundred times more tonnage in a single load than ourpioneer miners handled in an entire week. A similarrevolution has taken place in the explosives end of thebusiness: Black powder and hand steel have given wayto multi-gang hydraulically operated percussion drillscapable of drilling hundreds of feet of blast hole in asingle 8-hour shift, which, when loaded with modern-day explosives, break hundreds of thousands of tonsin a single blast. The downside of this modernizationand efficiency is that piles of non-ore-bearing rockand other waste streams have grown enormously. Themagnitude of environmental problems has soared, andwe have all become more cognizant of the fragility ofour environment.

Our increasing population is rarely perceived as partof the underlying problem; instead our ire is usuallyfocused on the laws that permit the development ofmineral deposits in the first place. The days are goneforever when an individual or a company could devel-op and mine a mineral deposit on and within lands ofthe United States, whether under the purview of theAmerican Mining Law, the Minerals Leasing Act, orthe Saleable Minerals Act, without full environmentalcompliance. Anyone desiring to participate in suchactivity today is subject to superior laws and regula-tions (such as the Clean Air and Water Acts, NationalEnvironmental Protection Act, and dozens of others)administered at the federal, state, and local level.

Today, environmental, cultural, and a host of otherconsiderations are carefully weighed against the needto extract resources. If the former are deemed morecritical or socially valuable than the latter, a mine suchas that at U.S. Hill could quickly become part of his-tory or never make it through the permitting process.These issues will challenge us as we become more, notless, dependant upon a reliable stream of mineralcommodities. Balancing our need for them against thedesire for a pristine environment and the preservationof our cultural heritage will doubtless be among themore vexing issues of the future, because the earth isnot only our home but also our sole source of thoseresources.

Special thanks to Homer Milford and Spencer Wilson,both of whom have long shared and exchanged historicdata and photographs with the author; and to MeghanJackson for ferreting out information on the “Indian Paint”mines and the local pueblos micaceous pottery.



C H A P T E R O N E


26

Molycorp’s Questa molybdenum mine has been inoperation since 1918. For more than eighty

years the mine has been a strong source of economicvitality in northern New Mexico. Producing hundredsof millions of tons of molybdenum since its inception,the Questa mine continues to operate, providing avaluable natural resource to the world market whilefully committed to operating in a safe and environ-mentally responsible manner. This paper provides abrief history of Molycorp’s operations and insight onthe mine's present and future operations.

A HISTORY OF OPERATIONS

In 1914 two local prospectors staked multiple claimsin an area of the Sangre de Cristo mountain rangecalled Sulphur Gulch. During their exploration theydiscovered an unknown dark, metallic material. Thecommon belief at the time was that it was graphite,and it was rumored to have been used for a myriad offunctions from lubricating wagon axles to shoe polish.In 1917 a sample of the ore was sent out to beassayed for gold and silver. The report included amention of molybdenum and its rising value resultingfrom an increase in usage during World War I. Earlyin the summer of 1918 the R & S MolybdenumMining Company began underground mining of thehigh-grade molybdenum veins in Sulphur Gulch. OnJune 1, 1920, the Molybdenum Corporation ofAmerica was formed and acquired the R & SMolybdenum Mining Company (which later becameMolycorp).

By August of 1923 Molycorp had built its own on-site processing mill, which could produce 1 ton ofmolybdenum concentrate daily from 25 tons of ore.All molybdenum production during this period wasfrom high-grade molybdenite (molybdenum sulfide),with grades running as high as 35 percent molybde-num. This mill was one of the first flotation mills inNorth America. The mill was rebuilt several times andoperated continuously until 1956, when the under-ground mining operations ceased. In 1963 this millwas dismantled to make way for the current mill.

From 1957 to 1960 exploration by drifting, cross-

cutting, and core drilling methods was conductedunder the Defense Minerals Exploration Act. Aftercompletion of the contract, Molycorp continuedexploration, and in early 1963 core drilling from thesurface and underground was accelerated to determinewhether or not an open-pit mine was economicallyfeasible. By 1964 sufficient reserves had been blockedout to justify the development of an open-pit mineand the construction of a mill that could handle10,000 tons per day. Pre-production stripping wasstarted in September 1964, and the first ore from thepit was delivered to the mill in January 1966.

Production from the pit continued until August1982. During this period the mill capacity increasedto 18,000 tons per day, and the stripping rateincreased to 120,000 tons. At this time the mineemployed approximately five hundred workers. Alsoat this time, additional exploration drilling in the areaof the existing open pit delineated several other ore-bodies. The largest of the orebodies contained approx-imately 125 million tons of ore averaging 0.3 percentmolybdenum sulfide.

Molycorp was acquired by Union Oil Company ofCalifornia in August of 1977. In November 1978development of the existing underground mine began,

The History and Operating Practices ofMolycorp's Questa Mine

Anne Wagner, Molycorp, Inc.

Molycorp’s earliest workforce, ca. 1920.

with two vertical shafts bottoming out at approximate-ly 1,300 feet deep, and a mile-long decline was drivenfrom the existing mill area to the haulage level. Themill flotation area was modernized to accommodatethe higher-grade of underground ore. In 1982 miningfrom the open pit ceased, and in August 1983 the newunderground mine began operating. Employment atthis time reached approximately nine hundred work-ers.

In 1986 an extremely “soft” market caused the firstshutdown of the mine in recent history. The mine wasrestarted in 1989 and continued to operate untilJanuary 1992, when the mine was shut down againdue to low prices. The mine restarted in 1995, andmost of that year was devoted to mine dewatering andrepair. Production began in late 1996, and over thenext several years approximately 30 million pounds ofmolybdenum concentrate were produced. Develop-ment of the current orebody began in 1998.Production from this orebody began in October 2000.This orebody and three adjacent ones collectively havesufficient ore reserves for production to continue forseveral decades.

MINE OPERATIONS

The mine has operated by several methods over thepast eight decades. Initially, the mine was a small,underground working, with donkey-hauled ore carsdelivering ore broken up by workers to the surface. Inthe early 1960s Molycorp decided it was more techni-

cally feasible to mine the orebody via an open pit. For twenty years, miners at Molycorp blasted pit

rock to access ore. Because open-pit operations gener-ate much more non-ore-containing rock, the companydeveloped a system of disposal through the construc-tion of nine rock piles located throughout the site,common practice throughout the industry. Molycorpdisposed of several hundred million tons of rock intothese piles. Currently Molycorp is working to ensurethe long-term stability of these piles, including themitigation work on the Goathill North pile that isunderway.

In the late 1970s Molycorp determined that the ore-body was too deep to mine by an open pit. In 1982,after several years of development at a cost in thehundreds of millions of dollars, the current under-ground operation was opened. The mine is now anunderground gravity block cave mine, designed toproduce 18,000 tons of ore per day.

Blocking caving is a bulk mining method. It takes arelatively weak and fractured orebody and collapses itunder its own weight. The ore is then drawn downinto a series of excavation areas for sizing and trans-portation by mechanical belt to the surface for furtherrefinement and milling.

During the milling process, the molybdenum ore isphysically separated from the rest of the rock.Through the use of a flotation system, the molybde-num is literally “floated” to the top of the tank, and

Molycorp’s molybdenum mill and conveyor system with prod-uct in sling bags packaged for sale.

Molycorp’s underground workforce in 2003 standing inlift, ready for transportation into the underground



C H A P T E R O N E


28

the remaining material is carried by pipeline ninemiles to the tailings facility west of the village ofQuesta.

OPERATING PRACTICES

Since the mine began in 1918, accepted operationalpractices have changed. These changes have ledMolycorp to adopt and incorporate best managementpractices throughout its site. Always closely connectedwith the village of Questa, Molycorp is continuing towork with the village and other stakeholders to pro-mote successful economic opportunities in the com-munity.

Molycorp is using its resources to promote econom-ic development opportunities in two key ways. Thefirst is a comprehensive program to use local contrac-tors whenever possible, and if it is not possible, out-side contractors are encouraged to use local suppliersor subcontractors when possible. The second is a pro-gram that supports the use of local suppliers and ven-dors of materials as much as possible. In addition,Molycorp is collaborating with many of the stakehold-ers who have an interest in economic and social sus-tainability of the village of Questa.

Environmental practices have also changed over theyears as regulations and expectations have changed.Today, Molycorp is devoting significant efforts to envi-ronmental investigations, best management practices,mitigation, etc. as the company continues to mine.

Current best management practices along the RedRiver include collecting poor quality, shallow ground

water and treating it to improve the water quality ofthe Red River. Ongoing voluntary investigationsinclude annual monitoring and reporting on theaquatic biology of the Red River.

On the mine site Molycorp is collaborating with thestate of New Mexico, the village of Questa, and otherstakeholders to understand the extent of the instabilityof the Goathill North rock pile and to determine thebest approach for long-term stabilization of the rockpile in an expedient manner. Work on the mitigationproject began in July 2004 and is expected to be com-pleted in mid-2005.

Another significant effort on the rock piles is anextensive test plot program that was established in late2003. The purpose of the test plot program is to fur-ther refine an appropriate reclamation approach thatMolycorp will implement upon closure of the mine.This undertaking exemplifies the uniting of on-sitestudies, off-site research, and state-of-the-art technolo-gy. Twenty-three research test plots were constructedover 20 acres. The test plots consist of areas of variousslopes including level areas, and slopes with gradientsof 2:1 and 3:1. Various cover depths (zero, one, andthree feet) were placed on the plots to evaluate theeffectiveness of the cover for reclamation, and morethan 26,000 seedlings were planted by hand alongwith seeding of grass and other plants. It is anticipatedthat this research will redefine high-elevation reclama-tion in the western U.S.

THE FUTURE

Although Molycorp anticipates continuing operationsinto the future, planning for closure is also important.A reclamation plan is required by the New MexicoMining Act, but Molycorp believes planning for clo-sure goes beyond reclamation. Current best practice inthe industry means thinking and planning ten or eventwenty years ahead of developments when it comes toclosure. Molycorp is now working to shift the com-munity away from its dependency on mining throughsupporting other economic development opportuni-ties. Molycorp has also committed to continue operat-ing the mine even when prices for molybdenum drop,moving employees from mining to reclamation andremediation projects until prices return to economiclevels. Molycorp is committed to mining responsibly,protecting the environment, working safely, and part-nering with local communities to develop additionaleconomic opportunities so the communities remainviable into the future.

Molycorp tailings facility interim revegetation. As a routine prac-tice Molycorp caps the inactive tailings areas with soil and seedswith native species.



New Mexico is at the eastern edge of one of theworld's great metal-bearing provinces. Copper is

particularly important, with large and (in come cases)world-class deposits in Arizona, New Mexico, Utah,and Sonora, Mexico. Nevada and (to a lesser extent)the entire Southwest are well endowed with gold andsilver. Some of the largest molybdenum deposits inthe world are found in Colorado and New Mexico.This is the nature of metal deposits; they are relativelycommon in certain geologic settings and almostunknown in others. Prospectors have known thisintuitively for many years, and it was the prospectorwho found most of the important deposits in south-western North America.

The metals found in New Mexico deposits are oftenthe results of the interaction of hydrothermal (hotwater) solutions with a host rock. In some cases fur-ther enrichment takes place when cooler, meteoric

water (rain and snow melt) interacts with low-grademineralization to concentrate the metal through aprocess called supergene (“from above”) enrichment.Many of the deposits discovered so far in New Mexicoare the result of water-rock interactions. These sametypes of reactions can create environmental concernslater on when the deposits are developed.

The important fact is that metals occur in distinctminerals, and to recover the metals, minerals must beconcentrated through processing. As higher-gradedeposits are depleted, lower-grade deposits will sup-ply the metals that society needs. This is especiallyimportant in New Mexico, where low-grade stockpilesand tailings of earlier mining operations exist andcould be processed in the future for their metal con-tent. This becomes increasingly significant as techno-logical advances facilitate the economic recovery ofmetals from lower-grade ores.

Metal Deposits in New Mexico—How andWhere They Occur

Robert M. North, Phelps Dodge Chino Mines CompanyVirginia T. McLemore, New Mexico Bureau of Geology and Mineral Resources

Simplified porphyry copper system. Mineralization typicallyoccurs in and around porphyritic diorite, granodiorite, mon-zonite, and quartz/monzonite plutons, which are surrounded

by concentric zones of hydrothermal alteration. The porphyriticigneous intrusion is locally surrounded by copper and lead/zincbearing skarns.


COPPER DEPOSITS

Copper has historically been the most important metalproduced in New Mexico. Copper is prized as the sec-ond-best conductor of heat and electricity (after silver)and has many uses, especially in the generation andtransmission of electricity. Copper occurs in a numberof specific geological environments in New Mexico.Most important of these are the porphyry-copper andassociated contact metamorphic (or skarn) depositsmined in the southwestern part of the state (the Chinomine near Silver City). Sedimentary red-bed type cop-per deposits are fairly common in New Mexico buthave produced only small amounts of copper. Copperis also a byproduct of the mining of zinc and lead veinand volcanogenic massive-sulfide deposits.

Porphyry Copper Deposits

Porphyry copper deposits are the most importantmetal deposits both in New Mexico and worldwide.

These deposits occur in porphyriticigneous rocks and adjacent host rocks ofsmall igneous intrusions at shallowdepths within 1.2 miles (2 km) of thesurface in the earth's crust. The termporphyritic refers to a specific texture ofigneous rocks characterized by largecrystals “floating” in a finer-grainedmatrix, each representing a differentepisode of cooling. Not all porphyriticigneous rocks host economic mineraldeposits, although porphyritic texturesare commonly associated with metaldeposits. The molten rock or magmaintrudes cool host rocks. As the magmacools, it solidifies from the contacttoward the center of the intrusion.Volatiles in the magma, primarily steamand carbon dioxide gas, build up withinthe magma until the pressure fracturesthe solidified porphyry and host rocksabove the magma chamber.Hydrothermal solutions are releasedthrough these fractures and react withthe host rocks, altering them in a char-acteristic manner. Copper minerals aredeposited as a part of this interaction.Typically these deposits are very large,

some in excess of a billion tons of mineralized rock.Copper grade varies from about 0.10 percent copperto over 1 percent copper with 2–5 percent pyrite. Theimportant deposits in New Mexico at Chino andTyrone were relatively low-grade ore after this initialmineralization and were upgraded through thisprocess of supergene enrichment. The porphyry copperdeposits in New Mexico are 55–58 million years old.

Supergene enrichment occurs when rocks with highpyrite content come into contact with water in an oxi-dizing environment. When this happens, water, oxy-gen, and pyrite react to form sulfuric acid. This acidnaturally leaches copper from the mineral chalcopy-rite, putting copper into an acidic solution. Copperstays in solution as long as the solution is acidic andoxidized. However, when the acidic solution is neu-tralized, or conditions becoming reducing, the coppercomes out of solution. Typically in natural systems,conditions become reducing just beneath the watertable. When this happens, the copper in solution easi-ly combines with sulfur. The sulfur available in pyriteand the copper in solution combine and replace pyritewith the copper mineral chalcocite. This process pre-serves copper through chemical dissolution and sub-

30

Metal mining districts in New Mexico. Most of these districtsare not presently active.

C H A P T E R O N E

sequent enrichment. Otherwise the metal is eventuallylost through the erosion of copper-bearing rock bymechanical means. Without this process, depositssuch as Tyrone would never have been economic, andthe deposits at Chino would be much smaller.

Skarn Deposits

Deposits of copper and other metals can form whenhot magma comes into contact with relatively cool,reactive rocks such as limestone, resulting in the dis-tinctive rock termed skarn. The term skarn refers torocks with diverse origins but similar mineralogy.Commonly these rocks have significant calcium-bear-ing varieties of garnet and pyroxene, sometimes withsignificant quantities of magnetite. Although suchdeposits form in a number of geological environments,they are most common in the southwestern U.S.

Polymetallic Vein Deposits

Polymetallic vein deposits formed as a result of tecton-ic and igneous activity in the Southwest between 75and 50 million years ago and are found in a numberof districts. These veins exhibit different textures andmineralogy but are similar in form and age. The mostimportant deposits of this type in New Mexico are inthe Hillsboro, Pinos Altos, Bayard, and Lordsburg dis-tricts. Vein deposits occur where hot, metal-bearingsolutions that are formed near an igneous intrusionare channeled through fractures, typically fault zones.These hot-water solutions can deposit metallic miner-als when the physical or chemical conditions of thesolution change, or through an interaction betweenthe wall rock and solution. For example, something assimple as cooling the solution can cause precipitationof metallic minerals. Boiling the solution is a commonmechanism for precipitation of metals. Host rocks canbe sedimentary, intrusive igneous, or associated vol-canic rocks. Veins were typically worked for both baseand precious metals and locally contain uranium,tungsten, tellurium, and beryllium. Mineralogies andmetal associations are diverse, even within a district.

The ores from veins of this type have potential foruse as quartz-rich smelter flux, which can be animportant component of the smelting process. Nearlytwo million tons of mineralized siliceous flux has beenshipped from veins in the Lordsburg district tosmelters in New Mexico, Arizona, and Texas, forexample. Past production indicates that these veindeposits are small in size relative to porphyry copperdeposits.

Sedimentary Copper Deposits

Copper is deposited in sedimentary rocks either aspart of the sedimentary process or during the processof diagenesis, the compaction and solidification ofsediments into rock. The mineralized bodies typicallyoccur as lenses or blankets of disseminated and/orfracture coatings. The copper minerals are predomi-nantly chalcopyrite, chalcocite, malachite, and azuritewith local uranium minerals, galena, sphalerite, andbarite. Ore minerals in these sedimentary copperdeposits are typically associated with organic debrisand other carbonaceous material. Sedimentary copperdeposits are the world's second most important sourceof copper after porphyry deposits; however, no largecopper-producing deposits of this type are found inNew Mexico. The most important sedimentary copperdeposits in New Mexico were mined in theNacimiento district near Cuba and the Pastura districtnear Santa Rosa.

MOLYBDENUM DEPOSITS

Molybdenum in New Mexico has been produced as abyproduct of copper and uranium mining and is cur-

Typical porphyritic texture, in a quartz monzonite porphyryfrom the Orogrande district in Otero County, New Mexico.The large white crystals (phenocrysts) are feldspar.





rently produced from primary molybdenum depositsat Questa. Molybdenum is used in steel alloys, andmolybdenite, the most common molybdenum miner-al, is used as a lubricant.

Porphyry Molybdenum Deposits

Porphyry molybdenum deposits are large, low-gradedeposits containing tiny, disseminated veins of molyb-denum sulfides and are associated with porphyriticintrusions. They occur in three areas in New Mexico:near Questa, in the Nogal district (Lincoln County),and in the Victorio Mountains (Luna County). Thelargest deposits are at Questa in Taos County. Thedeposits consist of thin veinlets, fracture coatings, anddisseminations of molybdenite (molybdenum sulfide)in granitic host rock. The deposits are similar in formto the porphyry copper deposits described above butare probably younger, 35–25 million years old.

GOLD AND SILVER DEPOSITS

Gold and silver have been produced in New Mexicomostly as a byproduct of copper mining, but somedeposit types were mined primarily for their preciousmetals. Gold is used as a monetary standard, in jewel-ry, and in specialized electronic applications. Thistakes advantage of the fact that gold is malleable, agood conductor of electricity, and resistant to corro-sion. Silver is the best conductor of electricity andheat, allowing for specialized applications, as well.Most silver is used in photography, but it is also usedin jewelry and electrical components.

Volcanic-Epithermal Deposits

Gold and silver occur in deposits classed as epither-mal, a term for deposits formed high in the earth'scrust at relatively low temperature (less than 300° C).Epithermal mineral deposits in New Mexico (and else-where in the world) are found in structurally complexgeologic settings that provide an excellent plumbingsystem for circulation of hydrothermal fluids.Geologists studying deposits of this type establishedthe now-recognized association between epithermalmineral deposits and active geothermal (or hot spring)systems. However, there are many small hot springsystems with no gold or base metals associated withthem. The Mogollon district in Catron County is themost productive example of this type of deposit; otherproductive examples are the Steeple Rock, Socorro

Peak, Chloride, (near Winston), and Cochiti(Sandoval County) districts.

Carbonate-Hosted Silver (manganese, lead)Replacement Deposits

Carbonate-hosted silver (±manganese, lead) replace-ment deposits formed in southwestern New Mexicoapproximately 50–20 million years ago. The depositscontain predominantly silver and manganese oxides,in veins and as replacements in carbonate rocks. Morethan 20 million ounces of silver have been recoveredfrom deposits of this type, but gold is rare. Althoughsilver and manganese are the predominant metals,lead is next in abundance. Manganese has been pro-duced from the Chloride Flat, Lone Mountain, andLake Valley districts. Economically, the most impor-tant silver deposits are in the Lake Valley andKingston districts.

Great Plains Margin Deposits

Some of the state's largest gold deposits are foundalong a north-south belt roughly coinciding with themargin between the Great Plains physiographicprovince and the Basin and Range (Rio Grande rift)and Southern Rocky Mountain provinces. Thesedeposits have similar characteristics that, when con-sidered with their tectonic setting, define a class ofmineral deposits referred to as Great Plains margindeposits by workers in New Mexico. Most deposits areassociated with igneous intrusive rocks that are 38–23million years old. The veins have high gold/base metalratios and typically low silver/gold ratios in contrastwith high silver/gold deposits in western New Mexico.The most important deposits of this type are found atElizabethtown–Baldy, Old Placers, White Oaks, andOrogrande districts.

Placer Gold Deposits

Placer gold deposits were an important source of goldin New Mexico before 1902, but placer productionsince 1902 has been minor. The earliest reports ofplacer mining were in the 1600s along the northernRio Grande. In 1828 large placer deposits were foundin the Ortiz Mountains in Santa Fe County (OldPlacers district), which began one of the earliest goldrushes in the western United States. Most placerdeposits in New Mexico had been discovered by1900. It is estimated that 662,000 ounces of gold have

Estimated total production of major metal resources in New Mexico. Figures are subject to change as more data areobtained (these are conservative estimates). Tons = short tons, unless otherwise stated.

COMMODITY YEARS OF ESTIMATED QUANTITY ESTIMATED QUANTITY VALUE IN RANKING INPRODUCTION OF PRODUCTION CUMULATIVE VALUE ($) IN 2002 2002 ($) U.S. IN 2002

Copper 1804–pres. >10.2 million tons >13.5 billion 277,094 tons 419 million 3Uranium 1948–2001 >347 million pounds >4.7 billion 264,057 pounds 2.6 million —Gold 1848–2002 >3.2 million troy ounces >394 million 32,337 troy ounces 9.5 million —Zinc 1903–1991 >1.51 million tons >338 million — — —Silver 1848–1998 >117 million troy ounces >252 million 433,596 troy ounces 2.4 million —Molybdenum 1931–pres. >146 million pounds >214 million 7,339,117 pounds 24 million 5Lead 1883–1992 >367,000 tons >56.8 million — — —Iron 1883–1962 8.2 million long tons 17.3 million — — —Manganese 1883–1963 >1.9 million tons 5 million — — —Tungsten 1907–1956 1.1 million pounds 250,000 — — —Total — — 20 billion — 475.5 million —


been produced from placer deposits throughout NewMexico between 1828 and 1991. Only four districtshave each yielded more than 100,000 ounces of placergold: Elizabethtown–Baldy, Hillsboro, Old Placers, andNew Placers.

LEAD AND ZINC DEPOSITS

Lead and zinc commonly occur together and havebeen produced in several districts in New Mexico.Zinc has been the more important of the two; approxi-mately 1.5 million tons worth more than $338 millionhave been produced. Zinc's most important use is ingalvanizing of steel; it is also important in the manu-facture of brass and other alloys. Lead is used primari-ly in lead-acid batteries.

Volcanogenic Massive-Sulfide Deposits

Volcanogenic massive-sulfide deposits are polymetallic,stratabound deposits formed contemporaneously withsubmarine volcanism by hot saline brines. Modernanalogies to this type of mineralization include the“black smoker” deposits at ocean rifts. Volcanogenicmassive-sulfide deposits contain varying amounts ofbase and precious metals and are associated with rocksformed between 1,650 and 1,600 million years ago, orperhaps earlier. Four districts in New Mexico containknown deposits of this type: Willow Creek, Santa Fe,Rociada, and La Virgen. Only the Willow Creek dis-trict near Pecos has yielded any significant production.Many of the volcanogenic massive-sulfide deposits andsuspected deposits are found within or near wilder-

ness areas and probably will not be developed in theforeseeable future.

Carbonate-Hosted Lead/Zinc Replacement Deposits

Carbonate-hosted lead/zinc replacement deposits arefound in southwestern New Mexico and formedapproximately 50–20 million years ago. The depositsinclude replacements and minor veins in carbonaterocks. They are typically lead/zinc dominant, withbyproduct copper, silver, and gold. The near-surfaceoxidized zones were typically the most productive inthe past. Economically, the most important depositsare in the Magdalena, Victorio (west of Deming), andOrgan Mountains districts.

Polymetallic Vein Deposits

Polymetallic vein deposits with important lead andzinc production are found in a number of districts,particularly near Bayard. These veins exhibit differenttextures and mineralogy but are similar in form andage. The Bayard deposits are the only important lead-zinc producers of this type in New Mexico.


C H A P T E R O N E


34

Industrial minerals have been called the third worldof the extractive industry. They seem to trail the

invariably glamorous metals and the politicallycharged energy products. Metals have defined indus-trial ages, and energy has framed government policy.They are obvious in everyday life as steel automobilesand aluminum beverage cans, not to mention utilitybills and gasoline prices. What remains in the extrac-tive industry are the more than fifty diverse nonmetal-lic and non-fuel materials that tend to vanish intocommon products. Few people at a dinner party thinkof a bottle of wine as a melted and shaped blend ofsilica sand, feldspar, limestone, and soda ash encapsu-lating a liquid based on a fertilized crop and clarifiedwith bentonite, diatomite, and/or perlite; secured by aplastic “cork” filled with calcium carbonate and talc;and identified by a label of cellulose containing kaolin,calcium carbonate, and titanium dioxide.

Despite such a low profile, industrial minerals areessential for our modern society and contribute signifi-cantly to New Mexico's economy. New Mexico ranksfirst in the country in the production of potash, per-lite, and zeolites; second in humate; third in copperand pumice/pumicite; and fifth in molybdenum. Ourstate is also a significant producer of construction sandand gravel and crushed stone (10 million tons peryear valued at some $64 million), gypsum, anddimension stone.

Today the total value of non-fuel mineral productionin the state of New Mexico is almost $600 million, ofwhich industrial minerals constitute approximatelytwo-thirds. These industrial minerals have a positiveeffect on society. Potash from Carlsbad is a key ingre-dient in fertilizer, and salt helps to de-ice roads;travertine from Belen provides unique architecturalfeatures; zeolites in Sierra County promote animalhygiene and environmental cleanliness; perlite fromSocorro and Tres Piedras contributes to ceiling tilesand horticultural soils; and pumice from the JemezMountains and the Mogollon-Datil volcanic field putsthe stone in stone-washed jeans. Local limestone fromaround the state helps remove pollutants from theenvironment, and construction aggregates from NewMexican limestone, granite, sandstone, and volcanic

rocks support the construction boom and improve thestate's expanding infrastructure.

This important sector of the economy may representa viable development path for the future and help tooffset declining metal production. What is needed is aclear understanding of the differences between indus-trial minerals and metals; horror stories abound aboutmetal producers who wandered into non-metals usinga metal-mining mentality and were doomed to failure.

LOW PRICES—LOW PROFILE

One prime reason for this lackluster appreciation ofthe industrial minerals business is the relatively lowselling price, with most in the $10–$100 per ton cate-gory, though industrial diamonds, iodine, and somerare earths sell for more than $10,000 per ton. Whatmakes industrial minerals interesting is the large num-ber of tons produced and sold. An average price of $5–6 per ton for aggregates in the United States is unim-pressive until it is multiplied by the annual produc-tion rate of 2.5 billion tons generating sales of morethan $14 billion. To put metals in perspective: Thevalue of all non-fuel minerals and metals sold in theUnited States is approximately $38 billion, of which

Industrial Minerals in New Mexico—Different fromMetals, but Crucial and Complex

Peter Harben, Las Cruces, New Mexico

The U.S. Hill mica mine in Taos County.

$30 billion is for industrial minerals (half of which areaggregates) and $8 billion is for metals. The value ofcement sold in the United States is about equal to thecombined value of copper, gold, and iron ore.Nevertheless, the relatively low price per ton dictateswhether or not a mineral can be mined commerciallyand how far it can be shipped. Consequently, distanceto market is more important for the average industrialmineral than for a metal.

LOCATION, LOCATION, AND LOCATION

To borrow a realtors' phrase, three of the most impor-tant characteristics of most industrial mineral depositsare location, location, and location. Specifically, cer-tain industrial minerals like silica sand and limestonefor glass or ceramics are relatively common and inex-pensive and, therefore, restricted to servicing localmarkets; no local glass or ceramics plant means nomarket. Less common minerals like perlite or potash

Industrial minerals in New Mexico. Metals are also shown.



C H A P T E R O N E


36

can serve regional and even international marketsbecause the higher prices can absorb the cost of trans-portation, and competition may be more distant orless intense. Still rarer products like borates have lim-ited sources of supply and can service internationalmarkets. This need for proximity to the market is ofparticular relevance to New Mexico, where market

Industrial minerals by price.

demand is limited by a relatively modest regional pop-ulation and manufacturing base. For the most part,mineral use in North America is concentrated in thetraditional markets of the Northeast and Midwest and(more recently) the fast-growing southern states.Manufacturing in the West tends to be restricted andconcentrated and serves a relatively large area, thuslimiting viable mineral supply points. At the sametime, many manufacturing plants are moving offshore.For example, ceramics plants are moving from theUnited States to Mexico and Asia.

The geographic spread of industrial minerals isbeing extended through the increased use of elaborateprocessing techniques to develop value-added grades.Kaolin, for example, may be ground and air floated toproduce a low-cost filler used locally for rubber; waterwashed for use nationally as a fine, white filler inpaper; or floated, delaminated, calcined, and magneti-cally separated to produce a bright “engineered mate-rial” for use in lightweight coated grades of paper allover the world. In contrast, perlite is shippedunprocessed in its compact form and later expandedto a much larger volume close to the point of con-sumption.

SPECIFICATIONS, SOPHISTICATION, AND SERVICE

One key difference of industrial minerals is that theyare prized for a combination of several physical andchemical properties, whereas metals are generally val-ued for a specific element that is extracted from theore. Specifications for industrial minerals, therefore,may require a combination of physical characteristicssuch as whiteness, particle shape, size and size distri-bution, viscosity, oil absorption, as well as chemicalpurity and strict maximums on impurities such asiron or heavy metals. Each end use requires a differentset of specifications; in fact, industrial minerals areoften described by the end-use grade—for example,drilling-mud-grade barite, coating-grade kaolin, andrefractory-grade bauxite. The importance of the min-eral's end use is illustrated by the fact that titaniumminerals are included in the industrial minerals cate-gory because 95 percent of the consumption is as anoxide for pigment rather than as a metal for jet fight-ers or bicycles. Other metallics overlap into the indus-trial minerals camp because of their nonmetallicuses—refractory, chemical, and abrasive-grade baux-ite; refractory, chemical, and pigment-grade chromite;beryllium as beryllium oxide; etc.

In contrast, metal specifications are relatively sim-ple, and there is no “fingerprint.” Copper from New

$1–10/METRIC TONS

aggregatesanhydritegypsumsaltsand & gravel

$10–100/METRIC TONS

aplite magnesitearagonite nepheline syenitebentonite olivinecalcium carbonate phosphatescement pumicecelestite propylitedolomite saltfeldspar salt cakeilmenite zeoliteskaolin

$100–1,000/METRIC TONS

alumina magnesiteanatase micaandalusite monaziteattapulgite nepheline syenitebarite nitratesbauxite perlitebentonite petaliteborax rare earth oxidescalcium carbonate rutilechromite silicadiatomite sillimaniteflint clay spodumenefluorspar sulfurgarnet talcgraphite vermiculiteiron oxide wollastonitekaolin xenotimekyanite zircon

$1,000–10,000/METRIC TONS

antimony oxide graphiteasbestos rare earth oxidesbastnaesite rutilebromine synthetic zeolites

OVER $10,000/METRIC TONS

diamondsiodinerare earth oxides

Mexico works as well as copper from Zambia or Chile,and 14-carat gold from a family heirloom sells for thesame price as freshly poured bullion from Witwaters-rand, South Africa. Place value is relatively unimpor-tant in metals. Therefore, these undifferentiated metalscommand little or no consumer loyalty and are sold atpublished prices. In contrast, many industrial miner-als need to be characterized by a multitude of chemi-cal and physical characteristics and often require anexhaustive evaluation process in order to qualify foruse by a particular consumer or plant, which may beoptimized for material from a single mine. Thisrequirement tends to generate loyalty to the supplier,and this loyalty may be cemented further as the sup-plier works with the consumer to improve quality ordelivery methods, reduce transportation costs, developnew grades, etc.

In some cases, specifications can only be met byblending minerals from various sources. For example,graphite houses may blend graphite from China,Brazil, and Canada, and a large paper plant may workwith a blend of kaolin and ground calcium carbonate.Suppliers of industrial minerals tend to encouragecustomer loyalty through good service, consistentquality and delivery, and even joint technical research.This makes market penetration for a newcomer diffi-cult, because a lower price is not always a means towrest away a market share. To make matters still morecomplex, the selling price of industrial minerals isreached through negotiation between supplier andconsumer, based on the quantity purchased and theterms of the contract, rather than (say) the fixed mar-

ket price of gold set daily in London.If an industrial mineral fails to meet the industry

specifications on a consistent basis, then it is unlikelyto be sold regardless of price. In contrast, metals suchas gold or copper can be mined and refined with thesure knowledge that they can be sold at a priceapproaching a level dictated by a terminal market andpublished in the press or on the internet. In the caseof products like iron ore, the buyer can financiallypenalize the seller for higher levels of impurities suchas phosphorus or arsenic. This rarely happens withindustrial minerals; the product is simply rejected.

This increased sophistication has been encouragedby the advent of fast, automated methods of manufac-ture demanding raw materials with a high degree ofuniformity. This in turn has placed heavy responsibili-ties on the suppliers of raw materials and has reducedstill further the concept of “price is king” as it is in themetal markets. Today in the industrial minerals arenait is price plus quality, consistency, and service thatmakes for a complex and demanding business.

WITHOUT A MARKET, A DEPOSIT IS MERELY AGEOLOGIC CURIOSITY

Metals and nonmetals share some common ground—both require geologic exploration, mining, materialshandling, and processing designed to produce com-mercially viable materials. Even here there are excep-tions, as many large industrial mineral deposits areobvious surface outcrops or may be discovered inci-dentally during the process of drilling for oil, gas, or

The Harding pegmatite mine in Taos County during itsproductive years.

Fresh cut at the No Agua perlite mine in Taos County, ownedand operated by Harborlite Corporation. Note the stratifiedlayers of volcanic ash that are characteristic of the deposit.



38


neering sectors such as transportation. These differ-ences in end-use markets are reflected in variations indemand behavior. Capital cycles that affect metalstend to be more extreme than consumption cycles forindustrial minerals, which tend to lag behind. As con-sumer demand for industrial minerals advances, itgenerates pressures for the creation of new productioncapacity. The markets for industrial minerals areregarded as “steady” whereas metal markets tend to bemore volatile (however, when copper prices climbabove $1.00 per pound, industrial minerals become“boring” rather than “steady”). Some mining compa-nies find that the steadiness of industrial minerals—cat litter is still necessary during a recession, but anew washing machine can be delayed—is a goodcounterpoint to the volatility of metals.

water. Consequently, high-profile regional explorationprograms for common industrial minerals are ratherrare. More commonly, the many known industrialmineral deposits are continually evaluated based onlocation, transportation, quality, processibility, andmarket demands.

Industrial minerals are market driven, a fact encap-sulated in the saying that “without a market, a depositis merely a geologic curiosity.” This means that adetailed market study is required to test the econom-ics of a given project. However, most modern miningcompanies employ a crew of managers, accountants,lawyers, investor relation gurus, engineers of allstripes, plus the odd geologist and even botanist, yetvery few feel the need to engage in-house marketresearch help. At the same time, companies continueto build mines and plants on the fly, and explorationgeologists still scour the far corners of the world forindustrial mineral deposits without the slightestnotion of whether anything found can be sold at aprofit or even sold at all. The concept that industrialminerals demand strong market analysis in order tobecome viable and valuable is lost in the rush to drill,raise capital, engineer, construct, debug, and producea product on schedule.

There are important differences between the eco-nomic behavior of industrial minerals and metalsbased on their different end-use pattern, which inturn dictates the method of marketing required. Ingeneral, industrial minerals tend to be used more inthe non-durable consumer-goods sector of the econo-my, whereas metals are more in the durables and engi-

Split-face travertine at New Mexico Travertine in Belen.


C H A P T E R O N E

Documents

THE PHYSICAL AND HISTORICAL FRAMEWORK - … fissure in Earth's crust (the Rio Grande rift) that is six times deeper than the Grand Canyon and thirty times larger than the Rio Grande