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TenebrescenceWhen considering the world of rocks and minerals, we think of them as permanent. “Solid as a rock,” we say. And yet, as collectors, some of our most treasured pieces are the ones whose delicate crystal spires could be forever destroyed with little effort. We learn that some of the most lovely opals lose their brilliant flashing colors merely by being wetted. But, in the case of many hydrophane opals, the colors return as the stone dries. There is also another property possessed by a few rare stones that involves a different kind of change in appearance. It is called tenebrescence.Tenebrescence, also known as photochromism, is the ability of some minerals to change color when exposed to sunlight. More specifically, the color change occurs when the specimen is exposed to light of differing radiation wave lengths. It was first discovered in 1896 in Greenland when a piece of tenebrescent Sodalite, subsequently dubbed as Hackmanite, was broken and the pink color of the newly exposed surface turned white in the sunlight. The color returned when the specimen was kept in the dark for a while or when exposed to short wave UV light. You may remember Transition™ lenses, the popular eyeglass that darkened when the wearer walked out into sunlight. This is an example of the commercial use of the same effect in a synthetic material.While the vast majority of literature on the subject describes the tenebrescence process as endlessly reversible, some geologists who have worked with
tenebrescent minerals report that some specimens will ultimately lose their ability to change color. Heating a specimen always permanently destroys tenebrescence. Collectors should take note that amethysts from Globe, Arizona, have been shown to permanently lose their color when exposed to sunlight. Some Tugtupite will intensify in color when exposed to sunlight. And some Spodumene has been show to shown to deepen in color to a pink or purple when exposed to
high-energy radiation. Interestingly, Hackmanite from Afghanistan and Myanmar is tenebrescent in the reverse. It displays color while in the light and loses it in the dark.The cause of tenebrescence has been the subject of some study. The answers have only been partially discerned. As complicated as the hypotheses are, suffice to say that
it appears to involve electron sharing and activity on a molecular level. Various wavelengths of light add or decrease available electrons, changing the way in which the molecules bond, thus changing the color as we see it.As rare as Hackmanite is, it is even rarer to find a piece gemmy enough to be faceted. It is too soft to be practical as a ring, but could conceivably make a
nice pendant or brooch. Because of tenebrescence, only pieces that held their color in light would be worthwhile as jewelry. But, as a curiosity, any tenebrescent mineral specimen would be a welcome addition to any collection.
Victoria O’Toole, RIMH
See page 4 for more about hackmanite.
VOLUME 52, Issue 10 October, 2014 © 2014 RIMH
Photo by Peter Cristofono © 2014
Hackmanite, fluoresces orangeMoultonborough, NH
Phot
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Pet
er C
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Hackmanite (white sodalite)Moultonborough, NH
VOLUME 51, ISSUE 1 JANUARY, 2013 © 2013 RIMHRhode Island Mineral Hunters, Inc.
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Volume 52, Issue 10 Bowen-Lite October, 2014
RHODE ISLAND MINERAL HUNTERS ~ 2014OFFICERSPresident: . . . . . . . . . . . . . . . . . . . . . . . .Steve EmmaVice-President: . . . . . . . . . . . . . . . . . . . . Buck LeachSecretary: . . . . . . . . . . . . . . . . . . . . . . Jennifer DavisTreasurer: . . . . . . . . . . . . . . . . . . . . . *Dante Caprara
EXECUTIVE BOARDLouise Barbish, Tom Barbish, *James Brenek, Rachel Cesana, Don Fail, Joel Russo, *Chris Tremblay, Bill Wilson
DEPARTMENTS / COMMITTEESHistorian: . . . . . . . . . . . . . . . . . . . . . . . . .Bill WilsonMembership:. . . . . . . . . . . . . . . . . . . . *Tom BarbishField Trip Coordinator:. . . . . . . . . . . . . . . Joel RussoShow Chairman: . . . . . . . . . . . . . . . . . . . . . .Don FailLibrarian . . . . . . . . . . . . . . . . . . . . . . . . . . . Bill NealEditor: . . . Bruce Luscombe, [email protected]: . . . . . .Bruce Hecker, [email protected]
VISIT OUR WEBSITE: www.RIMH.us* indicates a new officer / board member / duty for 2014
OUR NEXT MEETING RIMH FIELD TRIPSField Trip Coordinator: Joel Russo 401-942-3394, 401-263-1076 (cell), [email protected]
You MUST call or e-mail the field trip leader at least 24 hours in advance to be included. ALWAYS give your
cellphone or home phone # in case of cancelation.
UPCOMING FIELD TRIPS
Date: Tuesday, October 14th at 7:00 PMPlace: CCRI (Community College of RI) 400 East St., Rt. 113, Warwick, RIRoom: 1130Speaker: TBA
Fields Trips . . . continued on page 3
Executive Board meets at 7 PMon the 1st Tuesday of the month.
Oct. 7th, 7 PMMeeting will be at: TBA
ROCKtoberFEST2014 RIMH GEM, MINERAL & FOSSIL SHOWOur annual mineral show is Oct. 25 & 26 and it’s approaching fast. This is our main educational and fund raising event.Please contact Don Fail, show chairperson, to see where you can help. All members are encouraged to volunteer time and help make this a big success.
Don Fail: [email protected]
NOTE: Still working on a 2nd Oct trip.Will send out a blanket e-mail when ready.
Oct. 4th & 5th - 9 AMHerkimer Diamonds
Crystal Grove Diamond Mine, St. Johnsville, NYThis is a chance to collect some of the world’s best quartz crystals. Over the years Crystal Grove has been a favorite and successful collecting spot for many of our members. There is also a nice campground with camper and tent sites, and 4 cabins on the premises. Daily collecting fees are $12 adults, $10 children 5-13, children 4 and under free. If you don’t want to go for both days, the drive takes 3.5 hours from Cranston. When calling Joel, please tell him your plan for length of stay. Go to their website for more detailed information and to make reservations at the campground. Also, there are several reasonably priced motels in the area.Destination: State highway 114, St. Johnsville, NYDate(s)/time of trip: Saturday and Sunday, October 04-05, 2014 9:00 am to 7:00 pmTrip leader: Joel Russo, 401-942-3394, 401-263-1076 [email protected] give Joel your cellphone or home phone # in case of cancelationCarpool/caravan location: None, Make own arrangementsType of collecting: Hard rock and/or digging/sifting dirtWhat can be found? Beautiful double terminated and clusters of brilliant water-clear quartz crystals. Also crystals in the dolomite matrix. Also crystals with anthraxolite on matrix.Tools/equipment: hammers & sledges, garden tools, wedges, prybars, spray bottle w/water, protective eyewear, close-toed shoes, and always, common sense. There are sanitary facilities at this site. You can either sift the dirt or work the hard rock walls.Clothing: Long pants, close-toed shoes, gloves, hat, dress for seasonal weather.
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Field Trips . . . continued from page 2
A Word to the Wise or “The Crystal That Got Away.”
How many of us hear those tall tales of the “fish that got away” or the great crystal they “lost.” A typical novice collector’s mistake to put something down, just for a moment, and when they look up its gone, poof, disappeared, camouflaged in with the thousands of other look-a-like rocks in the hole never to be found again. A likely story, but not entirely unfounded. Such is my sad, sad story. A story of that great Uvite Crystal, the one everyone goes “OOO, WOW, GEEZ!”Yes, it happened to me. And the circumstances, well, typical. Just digging and cracking rock when I look over to my left and Voila! What is that sitting right out in the open 10 feet from me sparkling in the sun? It took my breath away! I couldn’t believe my eyes! But there it was, a 2 inch wide 3 inch long Uvite Crystal undamaged, as perfect as the day it was formed. Come to me my precious. It was mine! Joel will attest to it. It was FINE! I was afraid to put it in my pocket lest it get scratched. So I thought I’d just put it down next to me and later wisk it off to my bag. As often happens, as I continued to dig and crack rock I must have moved around a bit more than I figured and when I looked up, it was gone. I searched high and low, up and down, over and under, in every nook and cranny. There is nothing more deflating of one’s ego than to know you had the prize in hand, you had the mythical Crystal, and you let the “big one” get away. Learn a lesson all you hunters of the great crystal, the gold nugget, the gemmy beryl, the elusive diamond. Learn and lament from one relegated to telling my sad story of the “big one” that got away. Steve Emma, RIMH
Uvite Crystals, Gouvernor, NY Photo by Steve Emma
Editors Note: Here’s a photo of one that didn’t get away. I’m sure we all can relate to this true story. BL
Special information: Please call 48 hrs in advance. Bring your bug spray!!! As noted above, children of all ages are invited. If you bring a small child, please pay attention to his/her activities. Children should not wander near other people digging and hammering – flying shards of rock can seriously injure a non-attentive child.DRIVING DIRECTIONS:
GPS COORDS: 43.050221 N -74.636638 WGet off at Exit 29 (Canajoharie/St. Johnsville), turn right off ramp. Go ¼ mile to first traffic light (Rt. 10), turn right and cross Palatine Bridge. Take left at next light (Rt. 5) and continue approximately 8 miles through Nelliston to St. Johnsville, NY. Turn right at the traffic light by Stewart’s Shops (Division St.), bear right at fork (approx. 1 mile above light), and continue to campground (approx. 4 miles).NOTE: The bridge across the Mohawk River at Fort Plain is being worked on for the foreseeable future. Cross the river at Canajoharie.
Dinosaur Footprints in Holyoke, MAVisit: www.thetrustees.org/ then type “dinosaur” in keyword search boxImagine small herds of dinosaurs on the shore of a shallow tropical lake as you enjoy a real, up-close look at their fossilized prints left in sandstone.What makes Dinosaur Footprints a special place? Maybe it’s the treasure trove of more than 130 tracks revealed in slabs of sandstone. Researchers believe these prints were left by small groups of two-legged, carnivorous dinosaurs, up to 15’ tall.The first dinosaur prints to be scientifically described are still here to be seen, preserved in sandstone since this valley was a sub-tropical mix of wetlands and shallow lakes, 190 million years ago. The larger Eubrontes prints were likely made by ancestors of the great Tyrannosaurus rex, standing up to 15’ tall and 20’ long. You can see hundreds of fossils not only from the four distinct two-legged dinosaurs, but also stromatolites, fish, plants and other ancient beings.Finally, look for the 20+ dinosaurs trackways, which formed the basis for the theory that dinosaurs travelled in packs or groups.Trail: A short trail parallels Route 5 northward from entrance to the location of footprints. Easy walking. Open: April 1 to Nov. 30, daily sunrise to sunset (closed in winter - icy conditions). Allow a minimum of .5 hour.You can download a pdf trail map from their website.
Bruce LuscomBe
390 Bridgetown rd.saunderstown, ri 02874
Featured BookFeatured this month is a book many of our club are familiar with. It’s “Dinosaurs in the Attic”, by Douglas J. Preston, former staff member and manager of publications for the NY Museum of Natural History.This book is a fascinating history of the museum, it’s founding, it’s difficult early year surviving Tammany Hall politics, through it’s golden age of exploration. It tells the stories of the determined and colorful men and women who risked their reputations and lives for science in such diverse and untamed places as the north pole and the Belgian Congo, Outer Mongolia, etc.The book is divided into two parts, the first being the history of the museum touched on above, and the second being an “armchair” grand tour of the museum properties and it’s many exhibits. Fossil buffs (we have a few) will love this book as the history of this museum is detailed in the many explorations for fossils through out the 19th century sponsored by the museum to fill many of the exhibits.Last but not least of the exhibits detailed is the Mineral and Gem exhibit. Some of the most extraordinary gems in the world are on display there. Though keeping these gems on display was not without its hazards as one of the greatest jewel heists in history was pulled off there.This is a must read for any rockhounder or history buff and our library will soon have a copy for loan. Bill Neal, RIMH Club Librarian
© Rhode Island Mineral Hunters ● “Bowen-Lite” newsletter ● October, 2014
The “Bowen-Lite” newsletter is produced by and for the members of the Rhode Island Mineral Hunters, Inc. (RIMH).All portions are copyright © 2014 - RIMH and/or the original author / photographer. www.RIMH.us
Hackmanite Field Trip???We don’t have to go to Ontario Canada to collect hackmanite. The pictured hackmanite is from Horne Quarry, Red Hill, Moultonborough, NH.With a little winter planning perhaps Joel can arrange a field trip to collect there and other area sites. Since Peter Cristofono has collected there in the past maybe he can give us some helpful information. We can also check out what Peter’s new book has to say about this collecting area. Available on Amazon.com: “Rock Hounding New England”
At the age of 11 one of my family’s first major collecting trips was to Bancroft, Ontario, Canda. They were hosting a huge mineral jamboree and all the area mines and collecting sites were open to collect at.One of the most exciting parts was hunting the old mine dumps for sodalite and hackmanite. Because hackmanite fades to white, ALL the rocks there were mostly white, sometimes showing a small vein of blue sodalite. You had to crack open every rock looking for the deep blue sodalite or the bright pink hackmanite hidden within or go at night with a UV light. Some specimens had both together which made them even more exciting to collect.We would take the faded hackmanite specimens and leave them under our UV lights overnight. In the morning we’d rush out to check our “recharged” pink rocks. Eventually we’d have to recharge them. Bruce Luscombe, RIMH
Here’s More:THINGS I LOVE ABOUT ROCKS!
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