GEOLOGICAL HANDBOOK

MINERAL B

BY: MAULANA ARSYAD

http://mineral.galleries.com/

THE MINERAL BABINGTONITE

Chemistry: Ca 2 Fe 2 Si 5 O 14 OH, Calcium iron silicate.

Class: Silicates

Subclass: Inosilicates

Uses: mineral specimen

Specimens

Babingtonite is a mineral that was unknown to science before the start of this century. It is an unusual mineral in three respects. It contains both divalent (+2) and trivalent (+3) iron ions and this causes a very weak magnetism that could turn the needle of a compass. It is opaque and brilliantly vitreous. It also is the only black mineral found with the typically white or pale colored zeolites. This sets it off and makes it easy to see the normally small crystals among the other minerals in a zeolitic pocket. Babingtonite is somewhat scarce and its presence in a specimen tends to raise the value of the specimen considerably. Babingtonite, although scarce, is found in almost all rare mineral collections. PHYSICAL CHARACTERISTICS:

Color is almost always black to dark green.

Luster is vitreous.

Transparency: Crystals are generally opaque but thin

crystals or splinters can be translucent.

Crystal System is triclinic; bar 1

Crystal Habits include short stocky prismatic crystals or

tabular to platy forms.

Cleavage is good in one direction and perfect in another,

these are pinacoidal but are at near right angles to each other forming rectangular prisms.

Fracture is uneven to subconchoidal.

Hardness is 5.

Specific Gravity is approximately 3.3 (somewhat above

average for translucent minerals)

Streak is brown to gray.

Associated Minerals are quartz, apophyllite, feldspars, heulandite, stilbite, scolecite and other zeolites.

Other Characteristics: weakly magnetic.

Notable Occurrences include Poona, India; Devon,

England; Baveno, Italy and several locations in Massachusetts.

Best Field Indicators are crystal habit, color, associations

with zeolites and luster.

THE MINERAL BAKERITE

Chemistry: Ca4B4(BO4)(SiO4) 3(OH)3 - H2O, Hydrated Calcium Boro-silicate Hydroxide.

Class: Silicates

Subclass: Nesosilicates

Group: Datolite

Uses: Only as mineral specimens.

Specimens

Bakerite is a rare boro-silicate that was discovered in Death Valley, California and is still only found in abundance there. It is found there in altered volcanic rocks as nodules and veins. Datolite and howlite a couple of other boro-silicates, form similar looking nodules, but datolite is harder and howlite is softer. Massive magnesite can also be confused with bakerite, but it has good cleavage. At another California locality, crystals and crusts of bakerite are found lining cavities in shale with crystals of celestite. The bakerite crystals are clearly

monoclinic with a slanted prismatic form. PHYSICAL CHARACTERISTICS:

Color is white, colorless or gray.

Luster is vitreous as crystals; dull to sub-vitreous

(porcelaneous) for nodules and masses.

Transparency crystals are opaque to translucent.

Crystal System is monoclinic; 2/m

Crystal Habits include prismatic, slanted (pseudo-

rhombohedral) crystals and cauliflower-like nodules and compact masses.

Cleavage is absent.

Fracture is conchoidal to uneven.

Hardness is 4.5

Specific Gravity is approximately 2.9 (average)

Streak is white.

Other Characteristics: Is non-fluorescent.

Associated Minerals include celestite and other minerals

in altered volcanic rocks.

Notable Occurrences include the type locality at Furnace

Creek, Death Valley, Inyo County and at the Sterling Borax Mine in Tick Canyon, Los Angeles County, California, USA.

Best Field Indicators are locality, nodular character,

hardness and non-fluorescence.

THE MINERAL BARATOVITE

Chemistry: KLi3Ca7(Ti, Zr)2(SiO3)12F2, Potassium Lithium Calcium Titanium Zirconium Silicate Fluoride.

Class: Silicates

Subclass: cyclosilicates

Uses: only as a mineral specimen

Specimens

Baratovite is a very rare silicate mineral. It is extremely new on the mineral scene since it was only described in the last twenty five years. Baratovite is a cyclosilicate which means that the structure is composed of silicate tetrahedrons linked together so that they form isolated rings. Baratovite is one of the rare minerals that are coming out of the former USSR and finding their way onto the mineral markets. Baratovite has the "look" of muscovite but is easily distinguished by its brilliant blue fluorescence under ultra-violet light. PHYSICAL CHARACTERISTICS:

Color is white with pinkish tints.

Luster is pearly.

Transparency crystals are transparent to translucent.

Crystal System is monoclinic (pseudo-hexagonal); 2/m

Crystal Habits include flattened pseudohexagonal crystals

also massive and lamellar.

Cleavage: perfect in one direction.

Fracture: uneven

Hardness is 3.5

Specific Gravity is approximately 2.9 (average)

Streak is white.

Other Characteristics: fluoresces brilliant blue under UV

light.

Associated Minerals include aegerine, misterite and other

rare silicates.

Notable Occurrences include Dara-Pioz, Tien-Shan

Mountains, Tadzhikistan.

Best Field Indicators are crystal habit, fluorescence,

cleavage, associations and locality.

THE MINERAL BARITE

Chemistry: BaSO4, Barium Sulfate

Class: Sulfates

Group: Barite

Uses: ore of barium

Specimens

Barite is a common mineral and makes very attractive specimens. It often is an accessory mineral to other minerals and can make a nice backdrop to brightly colored crystals. At times bladed or tabular crystals of Barite form a concentric pattern of increasingly larger crystals outward. This has the appearance of a flower and when colored red by iron stains, these formations are called "Desert Roses". Because Barite is so common, it can be confused for other minerals. Celestite (SrSO4) has the same structure as barite and forms very similar crystals. The two are indistinguishable by ordinary methods, but a flame test can distinguish them. By scrapping the dust of the crystals into a gas flame the color of the flame will confirm the identity of the crystal. If the flame is a pale green it is barite, but if the flame is red it is celestite. The flame test works because the elements barium (Ba) and strontium (Sr) react in the flame and produce those colors. PHYSICAL CHARACTERISTICS:

Color is variable but is commonly found colorless or white,

also blue, green, yellow and red shades.

Luster is vitreous.

Transparency crystals are transparent to translucent.

Crystal System is orthorhombic; 2/m 2/m 2/m

Crystal Habits include the bladed crystals that are

dominated by two large pinacoid faces top and bottom and small prism faces forming a jutting angle on every side. There are many variations of these faces but the flattened blades and tabular crystals are the most common. If the pinacoid faces become diminished or are absent, the resulting prismatic crystal has a rhombic cross section. Also scaly, lamellar, and even fiberous.

Cleavage is perfect in one direction, less so in another

direction.

Fracture is conchoidal.

Hardness is 3 - 3.5

Specific Gravity is approximately 4.5 (heavy for translucent minerals)

Streak is white.

Associated Minerals are numerous but significant associations have been with chalcopyrite, calcite, aragonite, sulfur, pyrite, quartz, vanadinite, cerussite and fluorite among many others.

Other Characteristics: green color in flame test (see

above).

Notable Occurances include Oklahoma, Connecticut and

Colorado, USA; England and Germany.

Best Field Indicators are crystal habit, flame test and

density.

THE MINERAL BASTNASITE

Chemistry: (Ce, La, Y)CO3F , Cerium Lanthanum Yttrium Carbonate Fluoride.

Class: Carbonates

Groups: Rare earth carbonates and Bastnasite.

Uses: As an important ore of cerium and other rare earth metals and as mineral specimens.

Specimens

Bastnasite, which is sometimes spelled as bastnaesite, is one of a few rare earth carbonate minerals. Other rare earth carbonate minerals include ancylite, baiyuneboite, burbankite, calcioancylite, calkinsite, carbocernaite, cebaite, cordylite, daqingshanite, donnayite, ewaldite, gysinite, huanghoite, hydroxylbasnasite, khanneshite, kimuraite, lanthanite, parisite, remondite, rontgenite, sahamalite, schuilingite, synchysite, tengerite, thorbastnasite and zhonghuacerite. Bastnasite has cerium, lanthanum and yttrium in its generalized formula but officially the mineral is divided into three minerals based on the predominant rare earth element. There is Bastnasite-(Ce) with a more accurate formula of (Ce, La)CO3F. There is also Bastnasite-(La) with a formula of (La, Ce)CO3F. And finally there is Bastnasite-(Y) with a formula of (Y, Ce)CO3F. There is little difference in the three in terms of physical properties and most bastnasite is bastnasite-(Ce). Cerium in most natural bastnasites usually far and away dominates the others. Bastnasite and the phosphate mineral

monazite are the two largest sources of cerium, an important

industrial metal. Bastnasite is closely related to the mineral parisite The two are

both rare earth fluoro-carbonates, but parisite's formula of Ca(Ce, La, Nd)2(CO3)3F2 contains a calcium (and a small amount of neodymium) and a different ratio of constituent ions. Parisite could be viewed as a molecule of calcite (CaCO3) added to two molecules of bastnasite. In fact, the two have been shown to alter back and forth with the addition or loss of CaCO3 in natural environments. Bastnasite forms a series with the mineral hydroxylbasnasite.

The two are members of a substitution series that involves the possible substitution of fluorine ions for hydroxyl (OH) ion groups. Hydroxylbasnasite has a formula of (Ce, La)CO3(OH, F). Not an obviously significant difference, but significant enough to warrant a new mineral. X-ray studies confirm that the hydroxyl ion groups increase the unit cells of the structure and crystallographically and mineralogically this is significant. Bastnasite gets its name from its type locality, Bastnas Mine, Riddarhyttan, Vastmanland, Sweden. Although a scarce mineral and never in great concentrations, it is wide spread and one of the more common rare earth carbonates. Bastnasite has been found in karst bauxite deposits in Hungary, Greece and the Balkans. Also found in carbonatites, a rare carbonate igneous intrusive rock, at Fen, Norway; Bayan Obo, Mongolia; Kangankunde, Malawi; Kizilcaoren, Turkey and Mountain Pass, California, USA. At Mountain Pass, bastnasite is the leading ore mineral. Some bastnasite has been found in the unusual granites of the langesundsfjord area, Norway; Kola Peninsula; Mont Saint-Hilaire mines, Ontario Canada and

Thor Lake deposits, Northwest Territories, Canada. Hydrothermal sources have also been reported. PHYSICAL CHARACTERISTICS:

Color is pale white, tan, gray, brown, yellow and pink.

Luster is pearly, vitreous, greasy to dull.

Transparency: Crystals are translucent to opaque.

Crystal System is hexagonal.

Crystal Habits include small hexagonal rounded flakes

and short prismatic crystals, also in rosettes and spheres as well as massive and granular. Bastnasite has been known to replace (pseudomorph) crystals of allanite.

Cleavage is distinct in one direction (basal) and poor in

three directions (prismatic).

Fracture is uneven.

Hardness is 4 to 4.5.

Specific Gravity is 4.7 to 5.0 (well above average)

Streak is white.

Associated Minerals are extensive and include albite, analcime, monazite, hematite, amphiboles, aegirine, rutile, rhodochrosite, ancylite-(Ce), calcite, apophyllite, cordylite, ashcroftine, fluorite, galena, donnayite, epididymite, apatite, serandite, zircon, elpidite, natrolite, pyrochlore, pyrophanite, astrophyllite, barite, brookite, leucophanite, lorenzenite, quartz, synchysite-(Ce), parisite, dolomite, strontianite, siderite and ankerite.

Notable Occurrences include the type locality at

Bastnas Mine, Riddarhyttan, Vastmanland, Sweden as well as Fen, Norway; Bayan Obo, Mongolia; Kangankunde, Malawi; Kizilcaoren, Turkey; langesundsfjord area, Norway; Kola Peninsula, Russia; Mountain Pass, California, USA; Hungary; Greece; several sites in the Balkans; Mont Saint-Hilaire mines, Ontario and Thor Lake deposits,

Northwest Territories, Canada.

Best Field Indicators: crystal habit, color, cleavage,

density, luster and locality.

THE MINERAL BAUMHAUERITE

Chemistry: Pb3As4S9, Lead Arsenic Sulfide

Class: Sulfides

Subclass: Sulfosalts

Uses: As a very minor ore of lead and arsenic and as mineral specimens.

Specimens

Baumhauerite is a rare sulfide mineral from the famous quarry at Lengenbach, Binnental, Valais, Switzerland. The site is famous for many rare minerals including: novakite, rathite, smythite, dufrenoysite, jordanite, marrite, seligmannite, wallisite, lengenbachite, bernardite, sartorite, arsenolamprite, liveingite, imhofite and hatchite to name a

few. Most of the more exotic minerals from this site are arsenic sulfides and sulfosalts like baumhauerite. Baumhauerite is usually a bright dark gray mineral with a nice luster and striated prismatic crystals embedded in a dolomitic marble. It is a rare mineral and is only found in a few localities. Lengenbach is the only locality where specimens can be found with regularity. PHYSICAL CHARACTERISTICS:

Color is a bright lead gray, blue gray to gray black

(internal reflections will flash a red color).

Luster is metallic to dull.

Transparency: Crystals are opaque.

Crystal System: Triclinic; bar 1.

Crystal Habits include prismatic striated crystals with

rounded faces; also in massive and granular forms.

Cleavage: Indistinct.

Fracture: Conchoidal.

Hardness is 3.

Specific Gravity is 5.3 (slightly heavier than average

for metallic minerals)

Streak is dark brown.

Associated Minerals include dolomite, realgar and sartorite.

Notable Occurrences are limited to the type locality of the Lengenbach Quarry, Binnental, Valais, Switzerland and Franklin, New Jersey, USA.

Best Field Indicators are crystal habit, locality, internal

reflections, associations and density.

THE MINERAL BAYLDONITE

Chemistry: Cu3Pb(AsO4)2 - H2O, Hydrated Copper Lead Arsenate Hydroxide

Class: PhosphateClass

Subclass: Arsenates

Uses: Crafted as cabochons and as mineral specimens.

Specimens

Bayldonite is another attractive arsenate mineral formed in the oxidation zone of ore deposits. It has a nice green color and high resinous luster. The color is mostly due to the copper content and the luster is mostly due to the lead content. Many specimens contain some zinc as well. Bayldonite, which was discovered at Penberthy Croft Mine in Cornwall, England, can be used to make attractive cabochons, but is also nice as cabinet specimens. Specimens are known from only a few localities, so treasure any that can be found. PHYSICAL CHARACTERISTICS:

Color is green to yellow-green or yellow.

Luster is resinous.

Transparency: Crystals are transparent to translucent.

Crystal System is monoclinic.

Crystal Habits include tabular crystals, radiating

fibrous, granular and massive crusts.

Cleavage is absent.

Fracture is uneven.

Hardness is 4.5

Specific Gravity is approximately 5.5 (well above

average for translucent minerals).

Streak is green.

Associated Minerals are duftite, mimetite, quartz, bindheimite, cerussite, wulfenite, mimetite, azurite and limonite.

Notable Occurrences include Penberthy Croft Mine

and Wheal Carpenter Mine, St. Hilary and St. Day, Cornwall, England; Arizona, USA and Tsumeb, Namibia.

Best Field Indicators are color, crystal habit, streak,

lack of cleavage, density, locality and associations.

THE MINERAL BEUDANTITE

Chemistry: PbFe3AsO4SO4(OH)6, Lead Iron Arsenate Sulfate Hydroxide.

Class: Sulfates; although sometimes classified as a Phosphate.

Group: Beudantite

Uses: As a very minor source of lead and as mineral specimens.

Specimens

Beudantite is a difficult mineral to classify in that it has both an arsenate anion group and a sulfate anion group. The arsenate anion would normally dictate that beudantite be classified in the Arsenate Subclass of the Phosphate Class of minerals. But

beudantite's sulfate anion group is intricate and essential in its structure, while the arsenate anion group can be substituted for by a phosphate anion group to at least a limited degree (see the Beudantite Group below). Many classification schemes place beudantite in the Phosphate Class however. Beudantite, which is named for the French mineralogist Francois S. Beudant, is at times a very attractive mineral. It can be beautifully colored although often too dark, appearing black. It has a nice high luster due to its lead content. It is often associated with other rare secondary minerals that are found in the oxidation zone of ore deposits. Often these assorted mineral specimens can be quite interesting and a bonus to the collector who likes lots of different minerals on one specimen (more for the money, so to speak).

Beudantite lends its name to a group of sulfate-arsenates and sulfate-phosphates called the Beudantite Group. These minerals are all trigonal, contain a sulfate ion group and have six hydroxides. The general formula of this group is AB 3{AsO4 and/or PO4}SO 4(OH)6. The A cation can be either calcium, barium, cerium, lead, strontium and/or hydrogen. The B cation can be either iron, aluminum and/or gallium. These are the members of the Beudantite Group:

Beudantite (Lead Iron Arsenate Sulfate Hydroxide)

Corkite (Lead Iron Phosphate Sulfate Hydroxide)

Gallobeudantite (Lead Gallium Arsenate Sulfate

Hydroxide)

Hidalgoite (Lead Aluminum Arsenate Sulfate

Hydroxide)

Hinsdalite (Lead Strontium Aluminum Phosphate

Sulfate Hydroxide)

Kemmlitzite (Strontium Cerium Aluminum Arsenate Sulfate Hydroxide)

Orpheite (Lead Aluminum Phosphate Sulfate

Hydroxide)

Schlossmacherite (Hydrated Hydrogen Calcium

Aluminum Arsenate Sulfate Hydroxide)

Svanbergite (Strontium Aluminum Phosphate Sulfate Hydroxide)

Woodhouseite (Calcium Aluminum Arsenate

Sulfate Hydroxide) THE PHYSICAL CHARACTERISTICS OF BEUDANTITE:

Color is green, dark green, yellow-green, orange-

brown, brown or black.

Luster is vitreous, adamantine to greasy.

Transparency: Specimens are transparent to translucent.

Crystal System is trigonal: bar 3

Crystal Habits include blocky rhombohedrons,

sometimes pseudo-cubic, and platy to tabular crystals. also as druses, crusts and earthy masses.

Cleavage is perfect in one direction (basal), but not

usually seen.

Fracture is conchoidal.

Hardness is 4.

Specific Gravity is approximately 4.3 - 4.5 (heavy for

non-metallic minerals).

Streak is greenish yellow.

Associated Minerals include mimetite, jarosite, conichalcite, anglesite, galena, sphalerite, arsenopyrite, pyrite, pyrrhotite, descloizite, aegirine, hemimorphite, microcline, muscovite, arthurite, tetranatrolite and natrolite.

Notable Occurrences include Tsumeb, Namibia; Mont Saint-Hilaire, Quebec, Canada; several mines in Arizona, USA; laurion, Greece and Australia.

Best Field Indicators are crystal habit, density, color,

streak, luster and hardness.

THE MINERAL BENITOITE

Fluorescent Cursor Passover

Chemistry: BaTiSi3O9, Barium Titanium Silicate.

Class: Silicates

Subclass: Cyclosilicates

Uses: As a gemstone and as a mineral specimen

Specimens

Benitoite is a somewhat obscure, but wonderful gemstone mineral that was only discovered at the beginning of this century. It has a sapphire blue color and was first thought to be a variety of sapphire. But x-ray studies showed that the crystal structure was unlike any mineral previously discovered. It is one of only a few minerals to crystallize in the bar 6 m 2 class called the ditrigonal-dipyramidal symmetry class. While this class is

techically hexagonal, it produces trigonal (triangular) looking crystals. Additionally benitoite is also a fluorescent mineral. Nearly all specimens of benitoite will fluoresce a beautiful pale blue color under UV light (see above). Benitoite is associated with a few rare minerals such as black-red neptunite, snow white natrolite and brown-yellow joaquinite. The only source of this rare combination occures at

San Benito, California. They are formed in fractures of a serpentine rock from hydrothermal solutions. These solutions contained a number of unusual elements such as barium, titanium, fluorine, iron, cesium, niobium, manganese and lithium in relatively high concentrations. How such a solution occurred and what other conditions caused the crystallization of these rare minerals is still not well understood. The rare clusters of blue benitoite and black neptunite on top of a crust of white natrolite produces a truly fantastic and a one of a kind mineral combination that is a must have for a serious mineral collector. PHYSICAL CHARACTERISTICS:

Color is typically blue, but also colorless and yellowish.

Luster is vitreous.

Transparency: Crystals are transparent to translucent.

Crystal System is hexagonal; bar 6 m 2

Crystal Habits include the flattened six faced

dipyramid that has a distinct triangle shape often modified by minor faces. Also found as small grains.

Cleavage is absent.

Fracture is irregular.

Hardness is 6 - 6.5

Specific Gravity is approximately 3.6 (above average)

Streak is white.

Other Characteristics: Nearly all specimens fluoresce blue under UV light.

Associated Minerals include serpentine, neptunite, natrolite, joaquinite, sanbornite, taramellite, albite and fresnoite.

Notable Occurrences include only the mines of San Benito County, California, USA for good excellent crystals. SW Texas produces tiny grains in eocene sands as well as some other California localities.

Best Field Indicators are crystal habit, fluorescence,

color, associations and locality.

THE MINERAL BERAUNITE

Chemistry: Fe6(PO4)4(OH)5 - 4H2O, Hydrated Iron Phosphate Hydroxide.

Class: Phosphates

Uses: Only as mineral specimens.

Specimens

Beraunite is a scarce, but popular phosphate mineral for collectors. It can have a nice color and luster and its rarity make it an ideal collection specimen. It is one of those minerals that contain two valences of iron and its formula could be written to reflect this fact as in :Fe{+2}Fe{+3}5(PO4)4(OH)5 - 4H2O. This chemistry reflects the fact that the mineral formed in not quite completely oxidized conditions, a situation that interests geochemists. The larger Fe{+2} ion occupies a separate and

distinct position in the structure of beraunite from the five other Fe{+3} ions. PHYSICAL CHARACTERISTICS:

Color is yellow, brown, red, green or yellow.

Luster is vitreous.

Transparency: Specimens are translucent to

transparent.

Crystal System is monoclinic.

Crystal Habits include acicular, tabular, encrusting or radiating fibrous crystals.

Cleavage is good.

Fracture is uneven.

Hardness is 3 - 4

Specific Gravity is approximately 2.9 (average).

Streak is yellow.

Associated Minerals include strengite, cacoxenite, strunzite, rockbridgeite and limonite.

Notable Occurrences include Cornwall, England;

Ireland; Germany; Palermo Mine, New Hampshire and Pennington County, South Dakota, USA.

Best Field Indicators are crystal habit, color,

associations, cleavage and streak.

THE MINERAL BERLINITE

Chemistry: AlPO4, Aluminum Phosphate

Class: Phosphates

Uses: Only as mineral specimens.

Specimens

Berlinite is a rare phosphate mineral first discovered at the Vestana iron mine, Nastum, Sweden. It would not be very outstanding except for the fact that it is the only known mineral to be isostructural with quartz. Isostructural means that they have the same structure although the two minerals have rather different chemistries. Quartz, SiO2, would seem to be very different from berlinite, AlPO4. But if the formula of quartz is written as SiSiO4 then the similarity is obvious. The reason that berlinite is able to have the same structure as quartz is because the aluminum and phosphorus ions are of similar size to silicon ions. Thus the same structure can be achieved since the aluminums and phosphorus can completely replace the silicons without alteration of the quartz structure. Unfortunately, berlinite rarely forms crystals. It would be fascinating to compare the crystals of berlinite to those of quartz. PHYSICAL CHARACTERISTICS:

Color is colorless, gray to pink or rose.

Luster is vitreous.

Transparency: Crystals are transparent to translucent.

Crystal System is trigonal; 3 2

Crystal Habits include granular masses and

disseminated grains.

Cleavage is absent.

Fracture is conchoidal.

Hardness is 6.5

Specific Gravity is approximately 2.6 (average for

translucent minerals)

Streak is white or gray.

Notable Occurrences include the Vestana iron mine,

Nastum, Sweden.

Best Field Indicators are locality, color, absence of

cleavage and hardness.

THE MINERAL BERYLLONITE

Chemistry: NaBePO4, Sodium Beryllium Phosphate.

Class: Phosphates

Uses: As a collector's gemstone and as mineral specimens.

Specimens

Beryllonite is a rare beryllium mineral. It is found at only a few places around the world. It can be cut as gems, but lacks color, fire and hardness to be a popular gemstone. The first and some of the best specimens of beryllonite have come from McKean Mt., Stoneham, Maine. It forms from pegmatitic dikes and can be easily confused with more common pegmatite minerals. PHYSICAL CHARACTERISTICS:

Color is colorless, white to pale yellow.

Luster is vitreous.

Transparency: Specimens are transparent to

translucent (especially when frosted).

Crystal System is monoclinic; 2/m

Crystal Habits include tabular to equant crystals as

well as rosettes and masses.

Cleavage is good in one direction (basal), fair in

several other directions.

Fracture is conchoidal.

Hardness is from 5.5 - 6

Specific Gravity is approximately 2.8 (average for translucent minerals)

Streak is white.

Associated Minerals include quartz especially rose quartz, feldspars especially a variety of albite called cleavelandite, elbaite, beryl and columbite.

Notable Occurrences are limited to McKean Mt.,

Stoneham and Newry, Maine, USA; the Sapucaia pegmatite, Minas Gerais, Brazil and Paprok, Nuristan, Afghanistan.

Best Field Indicators are crystal habit, color, hardness

and locality.

THE MINERAL BERTHIERITE

Chemistry: FeSb2S4 , Iron Antimony Sulfide.

Class: Sulfides

Uses: A minor ore of antimony and as mineral specimens.

Specimens

Berthierite is easily confused with the closely related mineral stibnite. The chemistry of berthierite differs from stibnite by having an additional sulfur and one iron ion. Characteristic wise, berthierite differs from stibnite in being found more frequently in acicular to fibrous clusters, having a brown streak and non flexible crystals. PHYSICAL CHARACTERISTICS:

Color is brownish gray to dark brown.

Luster is metallic.

Transparency crystals are opaque.

Crystal System is orthorhombic; 2/m 2/m 2/m

Crystal Habits include acicular, fibrous or radiating crystals.

Cleavage is perfect in the lengthwise direction.

Fracture is uneven.

Hardness is 2.5 - 3

Specific Gravity is approximately 4.6+ (average for metallic minerals)

Streak is a dark brown.

Other Characteristics: Crystals are not flexible.

Associated Minerals include quartz, stibnite and other sulfides.

Notable Occurrences include France; Rumania; Colorado, USA; England and Germany.

Best Field Indicators are crystal habit, streak,

softness and inflexibility of crystals.

THE MINERAL BERTRANDITE

Chemistry: Be4Si2O7(OH)2, Beryllium Silicate Hydroxide.

Class: Silicates

Subclass: Sorosilicates

Uses: An ore of beryllium and as mineral specimens.

Specimens

Bertrandite was named after Leon Bertrand, a French mineralogist, and is one of the more important ores of beryllium, second only to beryl. Bertrandite is closely tied to the gemstone mineral beryl in many ways besides its use as an ore for the same metal. The two are often associated together as bertrandite is an alteration product of beryl. At times bertrandite is growing on beryl crystals and at other times bertrandite has completely replaced the beryl crystals forming a pseudomorph. A pseudomorph is an atom by atom replacement of one mineral for another; replacing the chemistry and structure with a new mineral, but preserving the outward shape of the original crystal. Pseudomorph mean false shape. Bertrandite is found in beryllium bearing pegmatitic rocks and some hydrothermal veins. PHYSICAL CHARACTERISTICS:

Color is colorless, white and pale yellow.

Luster is vitreous to pearly.

Transparency: Crystals are transparent to translucent.

Crystal System is orthorhombic; m m 2.

Crystal Habits include tabular to platy crystals and

some prismatic forms. Often aggregates formed over crystals of beryl. Twinning is common. Pseudomorphs of bertrandite after beryl are also common.

Cleavage good in one direction lengthwise.

Fracture is uneven to conchoidal.

Hardness is 6-7.

Specific Gravity is 3.3-3.5

Streak is white to gray.

Other Characteristics: Some specimens have fluoresced green under UV light.

Associated Minerals are numerous and include of course beryl as well as quartz, albite, orthoclase, fluorapatite, micas, anatase, brookite, pyrite, fresnoite, analcime, calcite and cheralite.

Notable Occurrences include the type locality of Petit-Port and Barbin, Nantes, Loire-Atlantique, France aa well as Akca Tau and Kara-Oba, Kazakhstan; Zabytoe, Primorie, Russia; Spor Mountain and the Brush Beryllium Mine, Juab County, Utah; Harding Mine, New Mexico; Texas and Pala District, San Diego County, California, USA; China; Cornwall, England; Mongolia; Norway and Mexico.

Best Field Indicators include only one direction of

cleavage, crystal habit, color, association with beryl and hardness.

THE MINERAL BETAFITE

Chemical Formula: (Ca, Na, U)2(Ti, Nb, Ta)2O6(OH, F) , Calcium Sodium Uranium Titanium Niobium Tantalum Oxide Hydroxide Fluoride.

Class: Oxides and Hydroxides

Group: Pyrochlore

Uses: A minor ore of rare earth elements and uranium and as mineral specimens.

Specimens

Betafite is a popular uranium bearing mineral to collect. It is one of the few uranium minerals to form nice well shaped crystals. Betafite crystallizes in the isometric symmetry class and forms large octahedral and dodecahedral crystals that can weigh up to 100 kg. Frequently they are modified by other isometric forms and/or flattened when two opposing faces dominate the crystal. Well formed crystals of betafite are considered classics! Because betafite has rare earth elements such as thorium in its chemistry, it is one of several so called Rare Earth Oxides. Other rare earth oxides such as fergusonite, euxenite, aeschynite and samarskite have very similar properties to each other but lack betafite's typically well formed isometric crystals. Betafite is formed in rare earth rich, granite pegmatites, a slow cooling igneous intrusive rock, such as from the site in which it was named; Betafo, Malagasy Republic, Madagascar. It is also found in the contact metamorphic marbles that surround these

pegmatites. Although concerning the marbles there is a question as to whether they are actually the product of igneous carbonatites. As is the case at the other most notable locality for betafite; Bancroft, Ontario, Canada. At these and other localities, betafite is associated with several minerals common to these rocks such as quartz, feldspars, columbite, tantalite, zircon, biotite, thorite, allanite, fergusonite and other rare

earth minerals. Betafite is a popular and interesting mineral. Although lacking in color, it makes up for it in the large well formed crystals for which it is known. Remember, this is a radioactive mineral and should be stored away from other minerals that are subject to damage from radioactivity and of course human exposure should be limited ! PHYSICAL CHARACTERISTICS:

Color is black with a tint of yellow, brown or green.

Luster is earthy to metallic and sometimes vitreous when translucent.

Transparency: Crystals are generally opaque but

some translucent specimens are known.

Crystal System is isometric; 4/m bar 3 2/m

Crystal Habits typically include octahedral and

dodecahedral crystals that are often modified by other isometric forms and/or flattened when two opposing faces dominate the crystal; also found as granular and massive. Some crystals can be quite large and can weigh up to and slightly over 100 kg.

Cleavage is absent.

Fracture is conchoidal.

Hardness is 4 - 5.5

Specific Gravity is approximately 3.7 - 5.0 (heavy for

non-metallic, average for metallic minerals). Extreme variation caused by variable composition of component metals.

Streak is yellow to brown.

Other Characteristics: Slightly radioactive and

crystals/specimens are often coated with a yellow or green earthy coating.

Associated Minerals include quartz, feldspars, columbite, tantalite, zircon, biotite, thorite, allanite, fergusonite and other rare earth minerals.

Notable Occurrences include Betafo (hence the

name), Malagasy Republic, Madagascar; Silver Crater Mine, Bancroft, Ontario, Canada and less noteworthy sites in Russia; Spain; Peru; Pakistan; India; China; Norway and Brazil as well as California, Arizona, New Mexico and Colorado, USA.

Best Field Indicators are crystal habit, luster, fracture,

color, radioactivity, associations, environment and specific gravity.

THE MINERAL BERYL

Chemistry: Be3Al2(SiO3)6, Beryllium Aluminum Silicate

Class: Silicates

Subclass: Cyclosilicates

Uses: Gemstone, mineral specimens and source of beryllium

Specimens Also see variety specimens:

o Aquamarine Specimens o Emerald Specimens o Goshenite Specimens o Heliodor Specimens o Morganite Specimens

Beryl is often unknown to the general public, even the gemstone-buying public. However, it is one of the most important gem minerals. Beryl is colorless in pure form; it is the many different impurities that give beryl its varied coloration. Without these splendid color varieties, beryl would be a rather ordinary gemstone with only average fire and brilliance. Emerald is the green variety and Aquamarine is the blue

variety of beryl. Other colors of beryl are also used as gemstones but are not as well known.

The greenish-yellow variety is called Heliodor.

The pink variety is called Morganite.

The colorless variety is called Goshenite.

The name beryl is used for the red and golden varieties, which are simply called red beryl and golden beryl, respectively.

Emerald is highly prized and is one of the most valued gemstones. Its green color is peerless and all other green gemstones are compared to its intensity. Emerald specimens are often "flawed" with mineral inclusions and fractures; unlike other gems, these are considered part of the stones' "character." These flaws actually help determine natural from synthetically-produced stones. Uncut emerald specimens are rare on the mineral markets, probably because even low grade emeralds can carry a high price when cut as gems. Especially hard to find are true "in-matrix" specimens. Fakes are often produced with natural crystals glued into a "host" rock and then sold as an in-matrix specimen with a highly inflated price.

Aquamarine is also a popular gem although it does not command nearly as high a price as its green cousin. Uncut aquamarines are plentiful but relatively expensive, as would be expected of crystalline gemstone specimens. Large crystals of aquamarine are available on the open market and represent perhaps the largest raw gemstone specimens. PHYSICAL CHARACTERISTICS:

Color is varied and includes emerald green, blue to

blue-green, yellow, greenish-gold, red, colorless and pink.

Luster is vitreous.

Transparency: Crystals are transparent to translucent.

Crystal System is hexagonal; 6/m 2/m 2/m

Crystal Habits typically include the hexagonal prism

with pincoid terminations. The terminations are often modified by many different pyramidal faces which can sometimes produce a rounded termination in the rough shape of a used pencil eraser.

Cleavage is imperfect in one direction (basal).

Fracture is conchoidal.

Hardness is 7.5 - 8.

Specific Gravity is approximately 2.6 - 2.9 (average)

Streak is white.

Other Characteristics: Faces on large crystals are

often pitted, striated lengthwise and rough.

Associated Minerals include micas, quartz, euclase, calcite, tourmalines and some feldspars.

Notable Occurrences include Colombia and some African localities for emerald; Brazil, Russia and Pakistan for aquamarine; California, Brazil, Africa, and many other localities for other beryls.

Best Field Indicators are crystal habit, lack of good

cleavage, hardness and color.

THE MINERAL BIDEAUXITE

Chemistry: Pb2AgCl3(F, OH)2, Lead Silver Chloride Fluoride Hydroxide.

Class: Halides

Uses: Only as mineral specimens.

Specimens

Bideauxite was named for American mineralogist Richard A. Bideaux. Its type locality of Mammoth-St Anthony Mine, Tiger, Pinal County, Arizona, USA is famous for wonderful lead minerals. Other lead minerals from here include phosgenite, murdochite, crocoite, ramsdellite, vanadinite, dioptase, wherryite, creaseyite, pinalite, matlockite, cerussite, anglesite, boleite, leadhillite and galena. Bideauxite forms from the alteration of boleite crystals. The boleite in turn formed from the original lead sulfide ores. Bideauxite is a beautiful mineral. It forms well shaped cubic crystals that look like fluorite cubes. The color however is more

variable than most fluorite specimens which are either strongly colored or colorless, but usually not both. In bideauxite, there can be deep purple colors in the crystal cores with strikingly colorless exteriors. Also in the same specimens there can be deeply colored cubes nested beside perfectly colorless cubes. The lack of cleavage and greater density for bideauxite are diagnostic in distinguishing it from fluorite. Unfortunately for collectors, bideauxite is extremely rare and hard to find on the mineral market. Bideauxite and others minerals with similar chemistries belong to a division in the Halide Class called the Oxyhalides and Hydroxyhalides. These minerals have either oxygen or hydroxide groups in their chemistries. The oxygen atom in their chemistries might require their classification in the Oxides Class of minerals except that their structures are more tied to

the halide elements and the oxygens and hydroxides are kind of superfluous to the overall structure. Some other members of the Oxyhalides and Hydroxyhalides include boleite, chloroxiphite, kelyanite, botallackite, laurionite, paralaurionite, mendipite, fiedlerite, pinchite, penfieldite, yedlinite, atacamite, koenenite, diaboleite, zirklerite and paratacamite. Of these, only atacamite and boleite are

common enough to be seen at rock shows and in rock shops with regularity. THE PHYSICAL CHARACTERISTICS OF BIDEAUXITE:

Color is colorless, white, pale violet to lavender.

Luster is adamantine.

Transparency: Crystals are transparent to translucent.

Crystal System is isometric; 4/m bar 3 2/m.

Crystal Habits include cubic crystals that envelope boleite crystals and often completely replace them.

Cleavage is absent.

Fracture is uneven.

Hardness is 3.

Specific Gravity is 6.3 (very heavy for translucent

minerals)

Streak is white.

Other Characteristics: Index of refraction equals 2.192 (very high).

Associated Minerals include boleite, matlockite, cerussite, anglesite, leadhillite and galena.

Notable Occurrences include the type locality of

Mammoth-St Anthony Mine, Tiger, Pinal County, Arizona, USA and Chile.

Best Field Indicators are crystal habit, color, density,

luster, lack of cleavage and locality.

THE MINERAL BINDHEIMITE

Chemical Formula: Pb2Sb2O6(O, OH), Lead Antimony Oxide Hydroxide.

Class: Oxides and Hydroxides

Uses: A very minor ore of lead and antimony and as mineral specimens.

Specimens

Bindheimite is an alteration product, or more specifically an oxidation product of lead antimony sulfides such as jamesonite, Pb4FeSb6S14 and boulangerite, Pb5Sb4S11.

Sometimes it pseudomorphs these minerals meaning that it replaces them without to much distortion of the outward appearance of the crystals. More commonly, bindeimite replaces these minerals with cryptocrystalline indistinct masses or crusts. PHYSICAL CHARACTERISTICS:

Color is yellow to red-brown or greenish to white.

Luster is resinous to earthy.

Transparency: Crystals are opaque.

Crystal System is isometric.

Crystal Habits include pseudomorphs of lead antimony sulfides, but more commonly cryptocrystalline masses or crusts.

Cleavage is not discernible.

Fracture is earthy.

Hardness is 4 - 4.5.

Specific Gravity is approximately 7.3 - 7.5 (heavier

than average) when pure but lowers with hydration to around 4.6.

Streak is pale yellow to brown.

Associated Minerals include stibiconite, tetrahedrite, partzite, lewisite, cerussite and other lead and/or antimony minerals.

Notable Occurrences include Nerchinsk, Siberia,

Russia; Bolivia; Australia; England; Cochise and Pima Counties, Arizona; Black Hills, South Dakota and San Bernardino County, California USA.

Best Field Indicators are crystal habit, color,

associations and luster.

THE MINERAL BIOTITE

Chemistry: K (FE, Mg)3 AlSi3 O10 (F, OH)2, Potassium iron magnesium aluminum silicate hydroxide fluoride.

Class: Silicates

Subclass: Phyllosilicates

Group: Micas

Uses: heat insulator for industrial purposes.

Specimens

Biotite is a common rock forming mineral, being present in at least some percentage in most igneous and both regional and contact metamorphic rocks. The typical black to brown color of biotite is characteristic although it is difficult to distinguish brown biotite from dark brown phlogopite. The two are actually end members in a series that is dependent on the percentage of iron. Phlogopite is iron poor and biotite is iron rich. The darker color and density increase with an increase in the iron content. Biotite tends to form in a wider range of conditions than phlogopite which is limited mostly to ultramafic rocks and magnesium rich marbles and pegmatites. Biotite, like other micas, has a layered structure of iron magnesium aluminum silicate sheets weakly bonded together by layers of potassium ions. These potassium ion layers produce the perfect cleavage. Biotite is rarely considered a valuable mineral specimen, but it can accompany other minerals and compliment them. In Bancroft, Ontario Biotite forms large crystals with green apatite and hornblende. Single large plates or "books" of biotite can grow to considerable size and can make impressive mineral specimens. Weathered tiny crystals of biotite can appear

golden yellow with a nice sparkle producing a "fool's Gold" that has fooled many. PHYSICAL CHARACTERISTICS:

Color is black to brown and yellow with weathering.

Luster is vitreous to pearly.

Transparency crystals are transparent to translucent.

Crystal System is monoclinic; 2/m

Crystal Habits include tabular to prismatic crystals with

a prominant pinacoid termination. Biotite's four prism faces and two pinacoid faces form pseudo-hexagonal crystal "books". The sides of the crystal often tend to tapper and can have a "hard candy that has been sucked on, look". Also as lamellar or granular rock forming masses providing the luster for most schists and gneiss.

Cleavage is perfect in one direction producing thin

sheets or flakes.

Fracture is not readily observed due to cleavage but is

uneven.

Hardness is 2.5.

Specific Gravity is approximately 2.9 - 3.4+ (slightly above average)

Streak is white.

Associated Minerals are quartz, feldspars, apatite, calcite, hornblende, garnets and schorl.

Other Characteristics: cleavage sheets are flexible

and elastic, meaning they can be bent and will flex back to original shape.

Notable Occurrences include Bancroft and sudbury,

Ontario; Sicily; Russia and many other locallities around the world.

Best Field Indicators are crystal habit, color,

cleavage, elastic sheets and associations.

THE MINERAL BISMUTH

Chemistry: Bi, Elemental bismuth

Class: Elements

Group: Arsenic

Uses: An ore of bismuth and as mineral specimens.

Specimens

Bismuth is rarely found in nature in its elemental form. Of growing interest in rock shops, however, are laboratory-grown bismuth crystals. These crystals, while not natural, are nonetheless very interesting to the mineral hobbyist and to others. The unique look that these clusters offer is really indescribable. Its color consisits of iridescent metallic yellow, blue and green hues. Of interest to hobbyists are the pseudocubic "hopper" crystals that are always present on the laboratory produced specimens, they are not seen in but only the rarest of natural crystals. Hopper crystals are a unique crystallographic curiosity Just the edges extend outward from the center of the crystal leaving hollow stairstep faces between these edges. The hopper crystals form due to the disparity of growth rates between the crystal edges and the crystal faces. PHYSICAL CHARACTERISTICS:

Color is silver white often with a multi-colored

iridescent tarnish.

Luster is metallic.

Transparency: Crystals are opaque.

Crystal System is trigonal; bar 3 2/m

Crystal Habits include mostly massive foliated forms in

natural specimens, although there do exist some well formed natural crystals they are rather scarce. Laboratory grown crystals display trigonal hopper crystals that appear pseudocubic.

Cleavage is perfect in one direction (basal)

Fracture is uneven or jagged.

Hardness is 2 - 2.5

Specific Gravity is 9.7 - 9.8 (unusually heavy even for

metallic minerals)

Streak is silver to white.

Other Characteristics: striations on cleavage

surfaces.

Associated Minerals include bismuthinite and ores of

cobalt and silver found in hydrothermal veins such as cobaltite and acanthite.

Notable Natural Occurrences include Australia; San

Baldomero and La Paz, Bolivia; Devon, England; Germany and South Dakota, Colorado and California, USA.

Best Field Indicators are tarnish, density and

cleavage. Hopper crystals in laboratory specimens are unmistakable.

THE MINERAL BISMUTHINITE

Chemistry: Bi2S3, Bismuth Sulfide

Class: Sulfides

Uses: An ore of bismuth and as mineral specimens.

Specimens

Bismuthinite is an important ore of bismuth. Sprays of steel gray prismatic bismuthinite crystals radiate outward from a common attachment point in the more spectacular specimens of this somewhat rare sulfide mineral. These specimens can not help but be compared to specimens of stibnite. It is difficult

to distinguish from the similar looking and closely related antimony sulfide. Bismuthinite is heavier than stibnite and on closer inspection of the crystals, there exists a noticeable difference with bismuthinite's having straighter, flatter faces. In massive form the confusion is even more pronounced, but bismuthinite is not associated with the typical antimony or arsenic minerals to which stibnite is so commonly allied. Associations of bismuthinite are varied, but combinations with the rare elemental mineral bismuth are particularly special. Chalcopyrite is another especially common associate. The carbonate mineral bismutite, Bi2(CO3)O2, is found as an

alteration (oxidation) product of bismuthinite and often is found as pseudomorphic crystals after bismuthinite. A pseudomorph is an atom by atom replacement of one mineral by another without significant changes in the outward appearance of the crystals (pseudo="false" and morph="shape").

PHYSICAL CHARACTERISTICS:

Color is steel gray to off-white.

Luster is metallic.

Transparency crystals are opaque.

Crystal System is orthorhombic; 2/m 2/m 2/m

Crystal Habits include radiating acicular to prismatic

columnar crystals. Sometimes in wonderful sprays that are similar to stibnite's crystal habits. Also granular

and massive.

Cleavage is perfect in one lengthwise direction.

Fracture is uneven.

Hardness is 2

Specific Gravity is approximately 6.8 - 7.2 (well above

average for metallic minerals)

Streak is gray.

Other Characteristics: Thin crystals are slightly

flexible, but inelastic. There maybe a slight yellow or iridescent tarnish present. Crystals are usually striated and have some sectility.

Associated Minerals are numerous and include gold, bismuth, bismutite, quartz, andradite, chrysoberyl, almandine, barite, scheelite, pyrophyllite, kettnerite, wulfenite, gadolinite, wolframite, beryl, epidote, microcline, pyrite, chalcopyrite, arsenopyrite, covellite and several other sulfides.

Notable Occurrences are many and include Cornwall, England; Bolivia; Australia; Temiscaming County, Quebec, Canada; Guanajuato, Mexico; Brazil; Kingsgate, New South Wales, Australia and some excellent locations in Vogtland and Siegerland, Germany. From the United States there are several localities in Haddam, Connecticut; Beaver County, Utah; Kern County, California; several counties in Arizona and in Boulder County, Colorado.

THE MINERAL BIXBYITE

Chemical Formula: (Mn, Fe)2O3, Manganese Iron Oxide

Class: Oxides and Hydroxides

Uses: A minor ore of manganese and as mineral specimens.

Specimens

Bixbyite is a rare mineral, but is still well known among collectors. It forms well formed isometric crystals, usually highly modified cubes. It also is associated with several interesting and attractive minerals and has a nice high luster. For these reasons bixbyite is popular among collectors although it only has an unimpressive black color and the crystals are usually small less than 1 centimeter wide. The associated minerals include pink and clear topaz, pink beryl, spessartine, quartz, hematite, hausmannite, braunite and pseudobrookite. These assortments are found in cavities in rhyolitic rock and make for attractive and much sought after mineral specimens. Especially wonderful bixbyite specimens come from the Thomas Range in Utah. The crystals of bixbyite are usually cubes. The corners can be modified by octahedral faces which truncate the corners with a single flat face. Also the faces of a dodecahedron can be seen modifying just the corners of the predominant cube with three faces per corner. If all three forms are present the crystal can look rather complex and beautiful. As an ore of manganese, bixbyite is often under appreciated. When found massive, it is usually associated with other

manganese oxides and is impossible to differentiate. Although iron can substitute for the manganese in the structure by over 50%, many bixbyite samples are nearly pure manganese oxide. PHYSICAL CHARACTERISTICS:

Color is dark black.

Luster is metallic to submetallic.

Transparency crystals are opaque.

Crystal System is isometric; 2/m bar 3

Crystal Habits include cubes often with octahedral and

dodecahedral faces modifying the corners. Also as massive and granular.

Cleavage is octahedral.

Fracture is uneven.

Hardness is 6.5

Specific Gravity is 4.9 - 5.0 (slightly above average for metallic minerals)

Streak is black.

Associated Minerals include beryl, quartz, spessartine, hematite, pseudobrookite, hausmannite, braunite and topaz.

Notable Occurrences are limited to the Thomas

Range, Utah; San Luis Potosi, Mexico; northern Patagonia, Argentina; Gerona, Spain; India; Sweden and South Africa.

Best Field Indicators are crystal habit, density,

hardness, associations and locality.

THE MINERAL BLODITE

Chemistry: Na2Mg(SO4)2 - 4H2O, Hydrated Sodium Magnesium Sulfate.

Class: Sulfates

Uses: Only as mineral specimens.

Specimens

Blodite, which is also spelled bloedite, forms in marine and non-marine (lacustrine) evaporite deposits. Evaporite minerals are geologically important because they clearly are related to the environmental conditions that existed at the time of their deposition, namely arid. They also can be easily recrystallized in laboratories enabling sedimentologists to obtain their specific characteristics of formation, such as temperature, solution concentrations, etc. Blodite also forms as an efflorescence on cave and mine walls. An efflorescent mineral is one that forms literally out of thin air, as a "precipitate" of sorts from fumes concentrated with the mineral's chemical makeup. Crystals of blodite are scarce, but well formed crystals can show an intricate, multi-facetted, monoclinic form. Specimens of blodite should be stored in a sealed container as they can dry out and crumble. PHYSICAL CHARACTERISTICS:

Color is white, colorless, gray, yellow. red, green or

blue-green.

Luster is vitreous.

Transparency: Specimens are translucent to

transparent.

Crystal System is monoclinic; 2/m.

Crystal Habits include granular, earthy and encrusting

masses. Individual intricate, multi-facetted, prismatic crystals are uncommon.

Hardness is 2.5 - 3.

Specific Gravity is approximately 2.2 - 2.3 (light for

translucent minerals).

Streak is white.

Other Characteristics: Salty taste.

Associated Minerals include halite, epsomite, alunite, thernardite, trona, sylvite and other more rare evaporite minerals.

Notable Occurrences include the type locality of

Chuquicamata, Antofagasta, Atacama Desert, Chile as well as Soda Lake and other California sites and Coconino, Arizona, USA; Germany; Russia; Austria; Poland and India.

Best Field Indicators are associations, density, crystal habit, taste and environment of formation.

THE MINERAL BOLEITE

Chemistry: Pb26Cu24Ag10Cl62(OH)48 - 3H2O, Hydrated Lead Copper Silver Chloride Hydroxide

Class: Halides

Uses: A very minor ore of silver, copper and lead and as mineral specimens.

Specimens

Boleite is a mineral of crystallographic curiosity and of great interest to collectors of twins, silver minerals and rare halides.

And hey . . . its pretty too! Its indigo blue color is distinctive and attractive and some crystals are cut as gemstones. Boleite is technically a tetragonal mineral and as such would form rectangular box-like crystals with a square cross-section. However, boleite is always pseudocubically twinned. In other words, each cube-like crystal of boleite is actually composed of three of these rectangular boxes oriented at right angles to each other. The pseudocubes are sometimes modified by tetragonal dipyramid faces which give the look of octahedral faces. Boleite is sometimes incorrectly listed as an isometric

mineral. Boleite is associated with a couple of other rare halide minerals; cumengite, (Pb21Cu20Cl42 (OH)40) and pseudoboleite, (Pb5Cu4Cl10(OH)8 - 2H2O) These halides have

similar chemistries to boleite and often form attached to the boleite crystals as epitaxial overgrowths. The cumengite/boleite combination crystal can form six pointed, 3-dimensional star shapes that are truly amazing.

These halides and others with similar chemistries belong to a division in the Halide Class called the Oxyhalides and Hydroxyhalides. These minerals have either oxygen or hydroxide groups in their chemistries. The oxygen atom in their chemistries might require their classification in the Oxides Class of minerals except that their structures are more tied to

the halide elements and the oxygens and hydroxides are kind of superfluous to the overall structure. Some other members of the Oxyhalides and Hydroxyhalides include bideauxite, chloroxiphite, kelyanite, botallackite, laurionite, paralaurionite, mendipite, fiedlerite, pinchite, penfieldite, yedlinite, atacamite, koenenite, diaboleite, zirklerite and paratacamite. Of these, only atacamite and boleite are common enough to be seen at rock shows and in rock shops with regularity. Boleite was named for its type locality at Boleo, Baja California, Mexico. The French colonial town of Santa Rosalia was built

near the copper mines that extracted copper from the unusual sedimentary copper deposits. Boleite crystals can still be found in these deposits although they are scarce and not easy to find. The chemistry of boleite is often written as the simpler Pb9Cu8Ag3Cl21(OH)16 - H2O. But this is not the most accurate portrayal of its chemistry. With its pretty color, valuable and interesting chemistry, rarity, history, associations and twinning; boleite is certainly a "must have" for any serious collector. PHYSICAL CHARACTERISTICS:

Color is deep blue almost black to a lighter indigo blue.

Luster is vitreous to pearly.

Transparency: Crystals are usually translucent but

some exceptional specimens are transparent.

Crystal System is tetragonal; 4 2 2

Crystal Habits include a pseudocubic habit due to penetration twinning of three individual "twins"

oriented perdendicular to each other. Often the crystal will appear to be modified by octahedron faces (actually pseudo-octahedral tetragonal dipyramids). The cubes are rarely over half an inch on each side. Individual twinned crystals are common and are often found loose without any host matrix.

Cleavage is perfect in one direction.

Fracture is uneven and brittle.

Hardness is 3 - 3.5

Specific Gravity is 5+ (rather heavy for translucent

minerals).

Streak is light greenish-blue.

Other Characteristics: Notches or interpenetrant

angles can be seen in some specimens revealing their true twinned nature.

Associated Minerals include other rare copper and lead chlorides such as pseudoboleite, cumengite, chloroxiphite, paralaurionite, matlockite, chlorargyrite, bideauxite, atacamite, mendipite and diaboleite. Also found with cerussite, smithsonite, leadhillite, linarite, phosgenite and chrysocolla. Boleite crystals are often loose, but some are found in a clay matrix.

Notable Occurrences include Boleo, Santa Rosalia, Baja California, Mexico; Broken Hill, New South Wales, Australia; Mammoth District, Arizona, USA and Mendip Hills, Somerset, England.

Best Field Indicators are crystal habit, color, density, streak and locality.

THE MINERAL BOLTWOODITE

Chemistry: K2(UO2)2(SiO3)2(OH)2 - 3H2O, Hydrated Potassium Uranyl Silicate Hydroxide.

Class: Silicates

Subclass: Nesosilicates

Uses: mineral specimen and a very minor ore of uranium.

Specimens

Boltwoodite is a locally common mineral but in general it is quite rare. It forms from the oxidation and alteration of primary uranium ore minerals. It forms crusts that are found on uranium bearing sandstones. The crusts have a yellowish color and a vitreous or silky to pearly luster. Remember, this is a radioactive mineral and should be stored away from other minerals that are affected by radioactivity and human exposure should be limited. PHYSICAL CHARACTERISTICS:

Color is yellow to pale yellow.

Luster is vitreous to silky or pearly.

Transparency: Crystals are transparent to translucent.

Crystal System: Monoclinic.

Crystal Habits are limited to crusts and tufts of fine

acicular crystals often found on uranium bearing sandstones.

Hardness is 3.5 - 4.

Specific Gravity is approximately 3.6 - 4.3 depending

on the amount of water (above average for translucent minerals)

Streak is pale yellow.

Associated Minerals are uraninite and other primary

uranium minerals.

Other Characteristics: Strongly radioactive.

Notable Occurrences are limited to Pick's Delta mine,

San Rafael Swell, Emory Co., Utah and Coconino County, Arizona, USA.

Best Field Indicators are environment of formation,

luster, color, locality and of course radioactivity.

THE MINERAL BORACITE

Chemistry: Mg3B7O13Cl, Magnesium Borate Chloride.

Class: Carbonates

Subclass: Borates

Uses: An ore of boron for boric acid and borax (a cleaning agent and useful industrial chemical) and as mineral specimens.

Specimens

Boracite is an interesting borate mineral. It has good color, clarity and hardness to be a gemstone and yet it is rarely cut for this purpose. Probably because it is slightly soluble in water and ordinary wear dulls its surface. It is an attractive mineral for mineral specimens though. Boracite is similar to quartz, in that it has high temperature and low temperature phases. The high temperature phase is cubic and forms nice well shaped cubes and octahedrons that are often modified by other isometric forms. The low temperature orthorhombic phase is the only phase that is stable at normal surface temperatures. This means that when the high temperature phase cools down, it converts to the low temperature phase. The conversion is easily accomplished and does not alter the outward appearance of the crystal, preserving the isometric forms. Therefore the specimens of boracite in a collection are actually the orthorhombic phase in the isometric crystal forms. Mineralogists refer to this as a pseudomorph, or "false shape". Boracite is an evaporite mineral and is not surprisingly found with other evaporite minerals like anhydrite, gypsum and

halite. Its crystals are often embedded in these other evaporite

minerals suggesting that they formed later than the others, especially since the crystals are in the high temperature phase. A variety of boracite is called "strassfurtite" and is a fibrous form found at Strassfurt, Germany. PHYSICAL CHARACTERISTICS:

Color is white to colorless and with pale tints of yellow,

green and blue.

Luster is vitreous.

Transparency: Crystals are transparent to translucent.

Crystal System is orthorhombic; 2/m 2/m 2/m ,

isometric; 4/m bar 3 2/m at high temperatures.

Crystal Habits include highly modified cubes and

octahedrons which are actually pseudomorphs of the high temperature isometric phase. Also massive, fibrous, nodular and as embedded grains.

Cleavage is absent.

Fracture is uneven or conchoidal.

Hardness is 7 - 7.5

Specific Gravity is approximately 2.9 - 3.0 (average

for translucent minerals)

Streak is white.

Other Characteristics: Slightly soluble in water.

Associated Minerals are anhydrite, gypsum, halite

and other evaporite minerals.

Notable Occurrences include Yorkshire, England; Strassfurt, Germany; Bolivia; Chactaw Salt Dome, Louisiana and Otis, California, USA and France.

BORAX

Chemistry: Na2B4O7 -10H2O, Hydrated sodium borate.

Class: Carbonates

Subclass: Borates

Uses: an ore of boron and as a source of borax (a cleaning agent and useful industrial chemical)

Specimens

Borax is a complex borate mineral that is found in playa lakes and other evaporite deposits. The basic structure of borax contains chains of interlocking BO2(OH) triangles and BO3(OH) tetrahedrons bonded to chains of sodium and water octahedrons. Most old mineral specimens of borax are chalky white due to a chemical reaction from dehydration. They have actually altered (at least on their surface) to the mineral tincalconite, Na2 B4O7-5H2O, with the loss of water. This kind of alteration from one mineral to another leaves the original shape of the crystal. Minerologists refer to this as a pseudomorph, or "fake shape", because the tincalconite has the crystal shape of the predecessing borax. Borax is directly deposited in arid regions from the evaporation of water in intermittent lakes called playas. The playas form only during rainy seasons due to runoff from adjacent mountains. The runoff is rich in the element boron and is highly concentrated by evaporation in the arid climate. Eventually the concentration is so great that crystals of borax and other boron minerals form.

PHYSICAL CHARACTERISTICS:

Color is white to clear.

Luster is vitreous.

Transparency crystals are transparent to translucent.

Crystal System is monoclinic; 2/m

Crystal Habits include the blocky to prismatic crystals

with a nearly square cross section. Also massive and as crusts.

Cleavage is perfect in one direction.

Fracture is conchoidal.

Hardness is 2 - 2.5

Specific Gravity is approximately 1.7 (very light)

Streak is white.

Associated Minerals are calcite, halite, hanksite, colemanite, ulexite and other borates.

Other Characteristics: a sweet alkaline taste, alters to

chalky white tincalconite with dehydration.

Notable Occurrences include Trona, Boron, Death

Valley and other California localities; Andes Mountains; Turkey and Tibet.

Best Field Indicators are crystal habit, color,

associations, locality, density and hardness.

THE MINERAL BORNITE

Chemistry: Cu5FeS4, Copper Iron Sulfide

Class: Sulfides

Uses: Major ore of copper and as mineral specimens.

Specimens

Bornite is an important copper ore mineral. It ranks up there with many of the other copper ores such as chalcocite, chalcopyrite, covellite, digenite, cuprite and tetrahedrite. As a mineral specimen, bornite is usually lacking. Good crystals are rare and thus bornite is commonly known as simply a massive mineral ore. It does however get used in the mineral trade as a curiosity called "peacock ore". A favorite among children, the bornite chunks sold as peacock ore or alternatively peacock copper have a rich bouquet of colors. The colors are from an iridescent tarnish that forms on bornite upon exposure to air. The tarnish is made of assorted copper oxides or hydroxides that form a mere atoms thin layer over the bornite. The thickness of the layers is close to the wavelength of light. When light waves bounce between the bornite surface and the top of the tarnish layer they will leave with the wavelengths of various colors. This effect is the same as the rainbow effect that occurs with oil on water. In the case of bornite, the tarnish will have a purplish, violet or blue color. Because bornite is often intergrown with chalcopyrite which tarnishes to more greens and yellows, the

peacock ore may have many colors ranging from purple to blue to green to yellow.

Bornite's crystals, if found, are usually distorted cubes with curved faces. Even rarer are the distorted octahedrons and dodecahedrons. These are isometric crystals. However,

bornite's structure at normal temperatures is not isometric. Bornite is only isometric at temperatures above 228 degrees celsius and it was above this temperature that the crystals formed. As bornite cooled it structurally altered to possibly a tetragonal structure but outwardly it retained the isometric forms. PHYSICAL CHARACTERISTICS:

Color is brown to black with a typical purplish-bluish

tarnish, a reddish bronze color on freshly broken surfaces.

Luster is metallic.

Transparency: Crystals are opaque.

Crystal System is isometric; 4/m bar 3 2/m above 228

degrees celsius but below this temperature its structure becomes less symmetrical possibly tetragonal; bar 4 2/m.

Crystal Habits include rare distorted cubes and even more rarely dodecahedrons and octahedrons. Most common habit is massive or disseminated grains.

Cleavage is very poor, octahedral.

Fracture is conchoidal.

Hardness is 3

Specific Gravity is approximately 4.9 - 5.3 (average

for metallic minerals)

Streak is a gray black.

Other Characteristics: The tarnish that occurs on

fresh surfaces can form in only hours and will become black over time.

Associated Minerals are magnetite, chalcocite, chalcopyrite, covellite, pyrrhotite, pyrite and other sulfides.

Notable Occurances include Bristol, Connecticut,

Butte, Montana, Plumas Co., Colorado and Superior, Arizona, USA; Cornwall, England; Rhineland, Germany; Tsumeb, Namibia; South Africa; Morocco; Bolivia; Chile; Peru and Mexico.

Best Field Indicators are lack of good crystals,

tarnish, streak, color of fresh surfaces and associations.

THE MINERAL BOULANGERITE

Chemistry: Pb5Sb4S11, Lead Antimony Sulfide

Class: Sulfides and Sulfosalts

Uses: Mineral specimens and as minor ore of lead.

Specimens

Boulangerite is one of a few sulfide minerals that form fine acicular crystals that appear as hair-like fibers. The fibrous aggregates may be so thick as to cover a specimen with hair-like fibers or it may be sparsely dessiminated between other minerals and may be confused with actual hairs or dark lint. Jamesonite and millerite are two other sulfides that form

similar acicular crystals and can be mistaken for Boulangerite. However, millerite is yellow and jamesonite has brittle crystals. Boulangerite is a sulfosalt, a segment of sulfides where the antimony acts more like a metal than a non-metal and occupies a position where it is bonded to sulfurs. Boulangerite and jamesonite have been called feather ores. A variety of boulangerite is called "plumosite" due to its plumose (feathery) habit and was thought to be a different mineral. PHYSICAL CHARACTERISTICS:

Color is blue lead gray to gray.

Luster is either metallic or silky.

Transparency: Crystals are opaque.

Crystal System: Monoclinic; 2/m

Crystal Habits include dense or sparse felted masses of acicular crystals. Also in fibrous and compact plumose (feathery) masses.

Cleavage is good in one direction parallel to the length.

Fracture is uneven.

Hardness is 2.5

Specific Gravity is 5.8 - 6.2 (heavier than average for

metallic minerals)

Streak is gray to brown.

Associated Minerals include pyrite, sphalerite, galena, siderite, quartz and arsenopyrite.

Other Characteristics: Crystals are flexible.

Notable Occurrences include Trepca, in the former

Yugoslavia; Pribram, in the former Czechoslovakia; Sala, Sweden; Hunan, China; Harz, Germany; Baja California, Mexico and at several locations in Idaho, Montana, Colorado, Washington and Nevada, USA.

Best Field Indicators are crystal habit, flexibility,

associations, color and luster.

THE MINERAL BOURNONITE

Chemistry: CuPbSbS3, Copper lead antimony sulfide

Class: Sulfides

Subclass: Sulfosalts

Uses: minor ore of lead and copper and as a mineral specimen

Specimens

Bournonite is also called "cog wheel ore" because of the cog wheel shape that the twinned crystals form. Twinning is common in bournonite and if a crystal repeatitively twins it can form a type of twin called a trilling. The trilling is composed of four "twins" or crystals connected in a plane and forms a wheel with a jagged edge that resemble the teeth of a cog wheel. Not all specimens show this type of twinning however. PHYSICAL CHARACTERISTICS:

Color is silver gray or black.

Luster is metallic.

Transparency crystals are opaque.

Crystal System is orthorhombic; 2/m2/m2/m

Crystal Habits include tabular to prismatic crystals.

Twinning is common and if repeated forms flat wheel shaped crystals called cog wheels. Also massive and granular.

Cleavage is poor in one direction.

Fracture is subconchoidal.

Hardness is 2.5 - 3

Specific Gravity is approximately 5.8 (above average

for metallic minerals)

Streak is black.

Associated Minerals are siderite, fluorite, galena, sphalerite, calcite and pyrite.

Other Characteristics: although the luster can be

bright, bournonite develops a dull tarnish. Crystals are usually striated on their sides which produces the "teeth" of the cog wheel.

Notable Occurrences include England; California,

USA; Mexico; Peru and Australia.

Best Field Indicators are crystal habit (especially twinning), color and density.

THE MINERAL BRASS

Chemistry: Cu3Zn2, Copper zinc

Class: Native Elements

Subclass: Metallic Alloys

Uses: Only as mineral specimens.

Specimens

Brass is not an officially recognized mineral as yet, although it has been proposed. It is not the man-made brass that is under consideration, but specimens of naturally occurring crystals of a copper nickel alloy with a formula similar to what we know as brass. These specimens are also not common, but are extremely rare and have only been found in a couple of localities in Siberia, Russia. Brass could be considered an official mineral if the naturally occurring crystals prove to have a unique structure and chemistry from other copper nickel alloys. That may prove difficult or impossible and if so, brass will then be discounted as a mineral. Brass is classified as an element dispite the fact, that in chemical reality, it is a compound. Minerals like brass are alloys with metallic bonds that are very similar to the more pure metallic elements and are thus classified as elements. PHYSICAL CHARACTERISTICS:

Color is yellow to brassy yellow.

Luster is metallic.

Transparency: Specimens are opaque.

Crystal System is isometric.

Crystal Habits are limited to tiny grains.

Cleavage is absent.

Specific Gravity is 8.4 - 8.7 (man-made brass)

Streak is brassy brown.

Notable Occurrences are limited to two localities in

Siberia, Russia; Tolbachik Volcano, Kamchatka and Vol'sk-Vym Ridge, Middle Timan.

Best Field Indicator is color, locality, density and

rarity.

THE MINERAL BRAZILIANITE

Chemistry: NaAl3(PO4)2(OH)4, Sodium Aluminum Phosphate Hydroxide.

Class: Phosphates

Uses: As a gemstone and as mineral specimens

Specimens

Brazilianite is an unusual gemstone mineral. It is one of the only phosphate minerals to be used as a serious gemstone. Although the phosphate mineral apatite is cut into gems it is not considered as precious as brazilianite. Of course brazilianite is relatively new to the mineral markets and is still not well known to everybody. It has a fair luster and interesting color, a yellow to greenish yellow. It may look a little like yellow topaz but brazilianite tends to be more green. Although not as hard as most other gemstones, it is one of the hardest phosphate minerals. Brazilianite is found in phosphate rich pegmatites. The igneous pegmatites are rather unusual for their phosphate content. Brazilianite was discovered in Brazil (hence the name) and was later discovered in New Hampshire at the Palermo Mine. The discovery at the Palermo Mine surprised many geologists who had studied the minerals there in detail and yet had "missed" this new mineral. PHYSICAL CHARACTERISTICS:

Color is yellow to greenish yellow and colorless.

Luster is vitreous.

Transparency: Crystals are transparent to translucent.

Crystal System: Monoclinic; 2/m

Crystal Habits include complex short prismatic and

wedge shaped crystals that seem to lack any symmetry. Crystals are very common, and massive examples are almost unknown.

Cleavage is perfect in one direction.

Fracture is conchoidal.

Hardness is 5.5

Specific Gravity is approximately 3.0 (average for

translucent minerals)

Streak is white.

Other Characteristics: Crystals are striated and the

index of refraction is 1.60 - 1.62

Associated Minerals are quartz, feldspars, muscovite and primary and secondary phosphates

associated with phosphate rich pegmatites.

Notable Occurrences include Conselheiro Pena and

other mines in Minas Gerias, Brazil and Smith Mine, Newport, New Hampshire.

Best Field Indicators are color, crystal habits, low

density and cleavage.

THE MINERAL BROCHANTITE

Chemistry: Cu4SO4(OH)6, Copper Sulfate Hydroxide.

Class: Sulfates

Uses: A minor ore of copper and as mineral specimens.

Specimens

Brochantite is a popular mineral for collectors and in some places it has been an important ore of copper. It typically forms acicular or fibrous crystals aggregated into randomly organized coatings and tufts. Its green color is usually a deep and attractive shade. It is formed from the oxidation of copper ore minerals along with other oxidation zone minerals. Brochantite is similar to other fibrous green copper minerals that form in oxidation zones such as the carbonate mineral malachite, the halide mineral atacamite and the closely related sulfate mineral antlerite. This brings up a number of identification problems. Acicular malachite will effervesce in warm hydrochloric acid and brochantite will not. Atacamite is slightly softer and is usually less transparent. Antlerite is all but indistinguishable by ordinary means although its terminations are typically flatter than the rounded terminations of brochantite. PHYSICAL CHARACTERISTICS:

Color is a bright emerald green or dark green to almost

black.

Luster is vitreous to pearly on cleavage surfaces.

Transparency: Crystals are transparent to translucent.

Crystal System is monoclinic; 2/m.

Crystal Habits include acicular or fibrous crystals

aggregated into coatings and tufts as well as small tabular crystals and reniform, massive or granular specimens. Terminations tend to be rounded or dome-like. Twinning is common and gives an orthorhombic

look to larger crystals.

Cleavage is perfect in one direction nearly

perpendicular to length.

Fracture is uneven.

Hardness is 3.5 - 4

Specific Gravity is approximately 3.9+ (above average

for translucent minerals)

Streak is green.

Other Characteristics: Does not effervesce in hydrochloric acid.

Associated Minerals are limonite, cuprite, chrysocolla, cyanotrichite, malachite, langite, posnjakite and azurite.

Notable Occurrences include numerous locations in

Chile; Ural Mountains, Russia; England; Italy; Romania; Zaire and several locations in Arizona, Nevada, California, New Mexico and Utah, USA.

Best Field Indicators are crystal habit, associations,

hardness, cleavage, non-reaction to hydrochloric acid and color.

THE MINERAL BROOKITE

Chemical Formula: TiO2, Titanium Oxide

Class: Oxides and Hydroxides

Uses: A very minor ore of titanium and as mineral specimens.

Specimens

Brookite is a polymorph with two other minerals. The minerals rutile and anatase as well as brookite all have the same

chemistry, TiO2, but they have different structures. At higher temperatures, about 750 degrees Celsius, brookite will automatically revert to the rutile structure. Rutile is the more common and the more well known mineral of the three. Brookite shares many of the same properties as rutile such as color and luster and some properties are nearly the same such as hardness and density. However due to structural differences brookite and rutile differ in crystal habit and cleavage. PHYSICAL CHARACTERISTICS:

Color is dark brown to greenish black.

Luster is adamantine to submetallic.

Transparency crystals are opaque.

Crystal System is orthorhombic; 2/m 2/m 2/m

Crystal Habits include the typical tabular to platy

crystals with a pseudohexagonal outline. Magnet Cove specimens tend to be more equant with complex facets.

Cleavage is poor prismatically and in the basal

direction.

Fracture is subconchoidal and uneven.

Hardness is 5.5 - 6

Specific Gravity is 3.9 - 4.1 (average for metallic

minerals)

Streak is light brown to white.

Associated Minerals include anatase, rutile, quartz, feldspars, chalcopyrite, hematite and sphene.

Notable Occurrences include Magnet Cove, Arkansas, Butte, Montana, Somerville, Massachusetts and Ellenville, New York, USA; Eicham, Austria; Tremadoc, Wales, England; Ural Mountains, Russia and at St. Gotthard, Switzerland.

Best Field Indicators are crystal habit, luster, density,

streak, associations and locality.

THE MINERAL BRUCITE

Chemical Formula: Mg(OH)2, Magnesium Hydroxide

Class: Oxides and Hydroxides

Group: Brucite

Uses: A minor source of metallic magnesium, a source of magnesia and as a refractory additive.

Specimens

Brucite is a mineral that is not often used as a mineral specimen but does have some important industrial uses. It is a minor ore of magnesium metal and a source of magnesia. It is also used as an additive in certain refractories. It is brucite's structure that is interesting. The basic structure forms stacked sheets of octahedrons of magnesium hydroxide. The octahedrons are composed of magnesium ions with a +2 charge bonded to six octahedrally coordinated hydroxides with a -1 charge. Each hydroxide is bonded to three magnesiums. The result is a neutral sheet since +2/6 = +1/3 (+2 charge on the magnesiums divided among six hydroxide bonds) and -1/3 = -1/3 (-1 charge on the hydroxides divided among three magnesiums); thus the charges cancel. The lack of a charge on the brucite sheets means that there is no charge to retain ions between the sheets and act as a "glue" to keep the sheets together. The sheets are only held together by weak residual bonds and this results in a very soft easily cleaved mineral. Brucite is closely related to gibbsite, Al(OH)3.

However the extra charge in gibbsite's aluminum (+3) as opposed to brucite's magnesium (+2) requires that one third of

the octahedrons to be vacant of a central ion in order to maintain a neutral sheet. Brucite is interesting for another reason because it is often found as a part of the structure of other minerals. How can this be? Well, the neutral magnesium hydroxide sheets are found sandwiched between silicate sheets in two important clay

groups: the Chlorite and Montmorillonite/smectite groups. The individual magnesium hydroxide layers are identical to the individual layers of brucite and are referred to as the "brucite layers". PHYSICAL CHARACTERISTICS:

Color is white or colorless with shades of gray, blue

and green.

Luster is vitreous or waxy; cleavage surfaces have a

pearly luster.

Transparency Crystals are translucent and rarely

transparent.

Crystal System is trigonal; bar 3 2/m

Crystal Habit is typically in flattened tabular crystals with rare rhombohedral terminations. Also found in lamellar and fibrous aggregates and as foliated masses. Brucite has been known to pseudomorph crystals of periclase.

Cleavage is perfect in one direction, basal.

Fracture is uneven.

Hardness is 2 - 2.5

Specific Gravity is 2.4 (slightly below average)

Streak is white.

Other Characteristics: cleavage flakes and fibers are

flexible but not elastic.

Associated Minerals are calcite, wollastonite, nepheline, talc, aragonite, serpentine, chromite, dolomite, magnesite, periclase and other magnesium minerals.

Notable Occurrences include Unst, Shetland Islands,

England; Aesbestos, Wakefield and Black Lake, Quebec, Canada; Aosta, Italy; Brewster, New York, Wood's Mine, Texas, Gabbs, Nevada, Crestmore, California and Berks Co., Pennsylvania, USA.

Best Field Indicators are crystal habit, luster

(especially on cleavage surfaces), lack of soapy or greasy feel and flexible but inelastic flakes and fibers.

THE MINERAL BUERGERITE

(A Tourmaline)

Chemistry: NaFe3Al6Si6O18(BO3)3O3F, Sodium Iron Aluminum Boro-silicate Oxide Fluoride.

Class: Silicates

Subclass: Cyclosilicates

Group: Tourmalines

Uses: Only as mineral collection specimens

Specimens

Buergerite is a rare species of the Tourmaline Group. Other more common and at least more well known tourmalines are schorl (black, opaque and iron rich), uvite and the gemstone mineral, elbaite (various colors, transparent to translucent and lithium rich). Buergerite is usually easy to distinguish from the more common tourmalines. It is generally brown and translucent to opaque. Buergerite is more easily confused with the lesser known tourmaline, dravite. It is very difficult to distinguish dravite from buergerite under normal circumstances since both are brown and only slightly translucent. However dravite is formed in metamorphic rocks and buergerite is found in some very unusual extrusive igneous rocks (volcanic rocks). Buergerite, when first discovered, was considered to be an unusual variety of schorl, another sodium iron tourmaline. But,

the iron in buergerite is different than in schorl. In schorl, the iron is in the plus two (+2) oxidation state, but in buergerite the iron is in a plus three (+3) oxidation state. This makes buergerite a rather unusual tourmaline. To compensate for the extra +3 charges (one extra charge from each of the three iron

ions in the formula) buergerite must substitute three of the four hydroxides (with a -1 charge each) , that are normally present in a typical tourmaline, for three oxygens (each with a -2 charge) in order to balance the formula. In addition to this odd-ball setup, buergerite has a fluorine (with a -1 charge) instead of that last hydroxide. Despite all of this chemical mayhem, buergerite still retains its tourmaline structure and most of the typical tourmaline characteristics. PHYSICAL CHARACTERISTICS:

Color is dark brown.

Luster is vitreous.

Transparency: Crystals are translucent to opaque.

Crystal System is Trigonal; 3 m

Crystal Habit is typically elongated three sided prisms.

The terminations can be either a simple to complex trigonal pyramid or a flat basal face. The prism faces are striated lengthwise. In cross section, all tourmalines will appear predominantly triangular in shape with some crystals showing a hexagon. Doubly terminated crystals are hemimorphic meaning that the two ends of the crystal are not exactly alike. Massive specimens can also be found.

Cleavage is absent although there is basal parting.

Fracture is uneven to conchoidal.

Hardness is 7 - 7.5

Specific Gravity is 3.3+ (slightly heavier than average)

Streak: Off white.

Other Characteristics: Pleochroic and piezoelectric.

Associated Minerals include those commonly found in

volcanic rocks.

Notable Occurrences is mostly limited to San Luis Potasi, Mexico.

Best Field Indicators are crystal habit, triangular

cross-section, locality, environment, color and hardness.

THE MINERAL BURBANKITE

Chemistry: (Na, Ca)3(Sr, Ba, Ce)3(CO3)5 , Sodium Calcium Strontium Barium Cerium Carbonate.

Class: Carbonates

Group: Rare Earth Carbonates.

Uses: Only as mineral specimens and as a possible source of cerium.

Specimens

Burbankite is a rare strontium and cerium carbonate mineral. Burbankite is one of many rare minerals that come from the famous mineral locality, Mont Saint-Hilaire, Quebec, Canada.

Some specimens have been cut from there and in fact a large 6.62 carat orange stone is the North American record holder for this species. But burbankite is far too rare to be considered a mainstream gemstone. Its crystal habit is reminiscent of apatite although its color and size is generally quite different. Burbankite's crystals are typically quite small but well formed and make good micromounts. Burbankite has some unusual chemistry as it is enriched in rare elements such as strontium, barium and cerium. Cerium is just one of the several rare earth metals that are important to industry. A closely related mineral is called carbocernaite.Both

minerals are considered to be important in the development of rare earth minerals in carbonatite rocks and are being studied for this reason. Some rare earth minerals have been found to make pseudomorphs of burbankite and carbocernaite. A testament perhaps of how they play a role in the rare earth minerals' development.

Some specimens of what was thought to be burbankite have been identified as a new species to science called remondite. Remondite has a different symmetry, monoclinic (although pseudohexagonal), and a slightly different chemistry. PHYSICAL CHARACTERISTICS:

Color is pale yellow, pale orange, beige, white and

colorless with some color zoning.

Luster is vitreous to dull or silky.

Transparency: crystals are transparent to translucent.

Crystal System is hexagonal.

Crystal Habits include small prismatic six and twelve

sided crystals with pyramidal or pinacoidal terminations. Also as compact spherical aggregates and fibrous masses.

Cleavage is distinct to imperfect in six directions (prismatic).

Fracture is uneven.

Hardness is 3.5 to 4.

Specific Gravity is 3.5 (above average)

Streak is white.

Other Characteristics: Some specimens have been known to fluoresce and rarely to exhibit an unusual

color change from green (in daylight) to brown (in incandescent light). Index of refraction is 1.615 - 1.627.

Associated Minerals are albite, calcite, donnayite, ilmenite, paranatrolite, pyrophanite, pyrite, sphalerite, astrophyllite, molybdenite, biotite, rutile, tetranatrolite, ewaldite, hilairite, anatase, andradite, barylite, catapleiite, cordylite, ancylite-(Ce), zircon, barite, analcime, synchysite-(Ce), natrolite and aegirine.

Notable Occurrences are limited to Mont Saint-Hilaire, Quebec and Chapman Lake, Ontario, Canada; Khibina, Kola Peninsula, Russia and the type locality

Vermiculite Prospects, Big Sandy Creek, Hill County, Montana, USA.

Best Field Indicators: crystal habit, color, luster and

locality.

THE MINERAL BUTTGENBACHITE

Chemistry: Cu19(NO3)2Cl4(OH)32 - 2H2O, Hydrated Copper Nitrate Chloride Hydroxide.

Class: Carbonates.

Subclass: Nitrates.

Uses: As a very minor ore of copper and as mineral specimens.

Specimens

Buttgenbachite is a rare copper nitrate mineral. Buttgenbachite is related to the sulfate mineral connellite. The two minerals are isostructural, share the same chemistry (except for the primary anion group) and have similar color and crystal habits. Connellite is a secondary mineral found in some unusual oxidation zones of copper deposits and is a classic mineral from the copper mines of Cornwall, England and Arizona,

USA. Buttgenbachite is much rarer than connellite. It was first discovered at Likasi, Shaba, now of the Congo. This was the only place of discovery until laboratory results proved its existence in a few samples from South Comobabi Mountains, Pima County, Arizona. PHYSICAL CHARACTERISTICS:

Color is deep blue.

Luster is vitreous.

Transparency: Specimens are translucent to

transparent.

Crystal System is hexagonal; 6 2 2.

Crystal Habits include acicular to fibrous crystals

arranged in tufts, layers or radial aggregates.

Cleavage is absent.

Fracture is uneven.

Hardness is 3

Specific Gravity is approximately 3.4 - 3.5 (slightly

above average for non-metallic minerals).

Streak is blue.

Associated Minerals include quartz and copper

minerals.

Notable Occurrence is limited to the Likasi, Shaba,

now of the Congo and South Comobabi Mountains, Pima County, Arizona, USA.

Best Field Indicators are crystal habit, color,

associations and locality.

THE MINERAL BYTOWNITE

Chemistry: Ca(70-90%) Na(30-10%) (Al, Si)AlSi2 O8, Calcium sodium aluminum silicate.

Class: Silicates

Subclass: Tectosilicates

Group: Feldspars

Uses: only as a mineral specimen.

Specimens

Bytownite is a rather rare member plagioclase series. The plagioclase series comprises minerals that range in chemical composition from pure NaAlSi3 O8, Albite to pure CaAl2 Si2 O8 , anorthite. Bytownite by definition must contain 30-10% sodium to 70-90% calcium in the sodium/calcium position in the crystal structure. The various plagioclase feldspars are identified from each other by gradations in index of refraction and density in the absence of chemical analysis and/or optical measurements. All plagioclase feldspars show a type of twinning that is named after albite. Albite Law twinning produces stacks of twin layers that are typically only fractions of millimeters to several millimeters thick. These twinned layers can be seen as striation like grooves on the surface of the crystal and unlike true striations these also appear on the cleavage surfaces. The Carlsbad Law twin produces what appears to be two intergrown crystals growing in opposite directions. Two different twin laws, the Manebach and Baveno laws, produce crystals with one prominant mirror plane and penetrant angles or notches into the crystal. Although twinned crystals are common, single

crystals showing a perfect twin are rare and are often collected by twin fanciers. PHYSICAL CHARACTERISTICS:

Color is usually white, gray or colorless but can be pale

shades of other colors.

Luster is vitreous to dull if weathered..

Transparency crystals are translucent to opaque and

only sometimes transparent.

Crystal System is triclinic; bar 1

Crystal Habits include blocky, or tabular crystals.

Rarely are free crystals seen but they have a nearly rectangular or square cross-section with slanted dome and pinacoid terminations. Twinning is almost universal in all plagioclases. Crystals can be twinned according to the Albite, Carlsbad, Manebach and Baveno laws. Bytownite is usually found as grains in gabbros and in compact masses.

Cleavage is perfect in one and good in another

direction forming nearly right angled prisms.

Fracture is conchoidal.

Hardness is 6 - 6.5.

Specific Gravity is approximately 2.74-2.76 (average)

Streak is white.

Associated Minerals are biotite, hornblende and pyroxenes.

Other Characteristics: index of refraction is 1.565 to

1.585. Lamellar twinning may cause a grooved effect on cystal and cleavage surfaces that appear as striations.

Notable Occurrences include Ottawa (formally Bytown), Canada; Scotland and South Africa.

Best Field Indicators are occurence, twinning

striations, density and index of refraction.