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The Mineral Newsletter Meeting: December 17 Time: 6:30 p.m. Long Branch Nature Center, 625 S. Carlin Springs Rd., Arlington, VA 22204 Volume 59, No. 10 December 2018 Explore our website! December Meeting: Holiday Party! (details on page 3) In this issue … Mineral of the month: Dioptase .............. p. 2 Club officer elections coming up .............. p. 2 Holiday party details—Food needed! ..... p. 3 The Prez Sez .............................................. p. 4 November meeting minutes..................... p. 4 Teaching minerals to Cub Scouts.............. p. 5 Take a better photo .................................. p. 8 Photo: Bob Cooke. Field trip opportunity ............................... p. 9 Humor ....................................................... p. 9 AFMS: Fossil sites for field trips ............... p. 10 EFMLS: Safety matters ............................. p. 11 Deadline for Submissions Bench tip: Mobile flexshaft stand............. p. 11 Origin of the chemistry set ....................... p. 12 December 20 The Ellensburg blue agate ........................ p. 13 Please make your submission by the 20th of the month! Submis- sions received later might go into a later newsletter. Upcoming events ...................................... p. 15 Mineral of the Month Dioptase Merry Christmas! by Sue Marcus Dioptase is our mineral of the month for Decem- Happy Hanukkah! ber—and it’s a beauty, known for its distinctive green color. I hope every collector has a specimen in her or his collection—or will get one soon. Dioptase used to be rare, though known from copper deposits in several parts of the world. Namibia started Club Elections Committee Report sending specimens to market, initially at very high The NVMC will elect club officers for 2019 at the prices. The costs decreased as supply increased, and December meeting before the holiday party. demand has always been steady for this pretty miner- al. Kazakhstan has also produced gorgeous dioptase Nominated are: specimens relatively recently, so there are options. President ......................... Sue Marcus With more specimens available, you can obtain Vice-President ................. Ti Meredith smaller ones—even nice ones—for relatively reason- Secretary ......................... David MacLean able prices. Of course, the crystals that are large, lus- Treasurer ........................ Roger Haskins trous, and undamaged still command top prices. The famous French priest and early mineralogist René Just Haüy (known as Abbé Haüy) named the mineral “dioptase” in 1797, from the Greek words dia (through) and optasia (to see), referring to the visibil- ity of cleavage planes within translucent to transpar- ent crystals. The original material described by Abbé Haüy came from Kazakhstan, which has a very long history of producing collectible minerals! The best known diop- tase locality is probably Tsumeb, Namibia, but other sources in Namibia and elsewhere in Africa have produced beautiful crystals. Namibia’s Kaokoveld District offers attractive specimens of dioptase with contrasting powder-blue shattuckite (see the photo on the right). Other sources include the Katanga (Shaba) region of the Democratic Republic of Congo (Zaire) and Renéville and Mindoula in the Republic of Con- go (Brazzaville). Another notable source is the Mal- Dioptase with shattuckite from Kaokoveld, Kunene region, paso Quarry in Córdoba, Argentina. Namibia. Photo: Bob Cooke. In the United States, dioptase is found in some of the carbonates or native copper) are much less expensive copper deposits in Arizona. The crystals are small to process for their copper content, so dioptase is not and don’t compete with those from foreign localities. a primary copper ore. Dioptase forms in arid envi- But they can appeal to someone who specializes in ronments where carbonates (such as limestone and collecting U.S. specimens or who wants to self- calcite) are present or chemically available. Fluids collect—and is lucky! rich in sulfuric acid leach the copper in the presence Dioptase is a hydrated copper silicate. It can be mined of a carbonate. The copper-rich fluids can deposit for its copper content, but other copper minerals (like dioptase, given enough time for the process to occur. And if we are really lucky, we get beautiful crystals. The Mineral Newsletter December 2018 2 Dioptase is a cyclosilicate, so when it crystal- lizes, its molecules are arranged in a ring struc- ture. Of course, the structure is at the micro- scopic level and not visible to the eye. At the macroscopic level, dioptase forms crys- tals in the trigonal system; a common example of a dioptase crystal is shown at left. However, the Goldschmidt Atlas of Crystal Forms shows 17 different forms in which dioptase can grow. Ground to powder, dioptase can be used as an artistic pigment, and it has been used as such since Neolithic times. Neolithic statues with dioptase as eyeliner have been found in Kazakhstan, so the mineral was mined Dioptase from Kaokoveld, Namibia. Photo: Bob Cooke. and used there long before anyone knew what it was. Due to its relative softness, dioptase is not durable as Color ................................. Green, usually deep a gemstone. It is sometimes used in wire-wrapped green; usually, color is distinctive jewelry, with the raw crystallized specimen display- Streak ................................ Green ing its lovely color. Cleavage ........................... 2 or 3 (sources vary!) Technical details: Fracture ............................ Irregular Chemical formula ............ Cu6Si6O18 ·6H2O Luster ................................ Adamantine, vitreous Crystal form ..................... Trigonal Sources Hardness: ......................... 5 Goldschmidt, V.M. 1986. Atlas of crystal forms. 9 Density: ............................ 3.3–3.4 volumes. Rochester, NY: Mineralogical Symposi- um. Mindat.org. 2018. Dioptase. Minerals.net. 2018. The mineral dioptase. Wikipedia. 2018. Dioptase. Wikipedia. 2018. René Just Haüy. Holiday Party December 17, 6:30‒9:30 p.m. The NVMC and the Micromineralogists of the National Capital Area are jointly hosting this year’s meeting and holiday party at the Long Branch Nature Center (our usual club meeting place). Great news—Dr. Mike Wise, geologist for the Smithsonian, will speak at our meeting! The NVMC and the Micromineralogists of the Na- tional Capital Area will provide fried chicken, honey- baked ham, and drinks for our holiday party. Please help round out our menu by bringing a side dish. We would appreciate salads, sides, desserts, and more. Dioptase with plancheite from the Mindoula District, Please click on the URL below for the app to sign up Republic of Congo (Brazzaville). Photo: Bob Cooke. if you are coming—and to sign up for a bringing a The Mineral Newsletter December 2018 3 dish. It really is very easy! Just click and follow the mineral show. And, as it stands now, we won’t have a directions! mineral show without Tom Taaffe. https://www.signupgenius.com/go/20F094AADAF2 The club needs more involvement. It’s hard enough AA46-northern to find people willing to be nominated for the four elected offices, and therefore those people serve re- Thank you. Looking forward to seeing everyone at peatedly over the years. I thought it remarkable that this wonderful holiday celebration! Rick Reiber served 8 years as club treasurer! Some- Holly Perlick and Marie Johnston one ask Tom how long he’s been show chairman. P.S.: If you would like to participate in the gift ex- Answer: Tom began as cochair with George Loud in change, please remember to bring a gift valued be- 1999, serving for the next 4 years. Since 2006, Tom tween $5 and $20. has served constantly as show chair or cochair. That’s a total of 23 years! It’s your club, so please step up! The Prez Sez Bob by Bob Cooke Finally! Meeting Minutes The Prez Sez edition that everyone has November 12, 2018 been waiting for—my last one. by David MacLean, Secretary It’s been 3 years, and it’s about time. I have tried my best. There have been some successes and some failures. There has definitely been a learn- President Bob Cooke called the meeting ing curve, and I’ll do my best to pass on those lessons to order at 7:45 p.m. at the Long Branch to your new club president. I fervently hope there Nature Center in Arlington, VA. won’t be any hanging chad or other issues to delay The minutes of the October 22 meeting were ap- the transition and force a recount. proved as published in The Mineral Newsletter. The As I write this edition of the Prez Sez, the annual president recognized past President Barry Remer. GMU/NVMC Mineral Show is still a week into the Old Business future. I hope all goes well! Over the last couple years, I have tried to fill in for Jim Kostka (but have Show Chair Tom Taaffe asked people to sign up to succeeded, at best, only partially) and to help Tom help run the club show on November 17–18 at the Taaffe in his efforts to put on this mineral show. But Hub at George Mason University. There might al- I’ve been only a helper; Tom is the main man. Re- ready be adequate help for show setup, but help is cently, Carolyn asked me what would happen if Tom especially needed at the kids’ tables; three groups of decided not to be show chair next year. I’m afraid the Boy and Girl Scouts are expected. answer is obvious: there wouldn’t be a mineral show. Announcements Many people think that because Tom is a dealer, he The joint NVMC/MNCA Christmas party will be on makes money at the show and is show chair only for Monday, December 17, at 6:30 p.m. You can find his own pocketbook. In fact, there are other shows he details on page 3. could attend on the same weekend as our club show and not have to invest his time in and deal with the Door Prizes frustration of organizing our show. He does our show Winners in the door prize drawings included Dave because it is our show. Hennessey, Kathy Hrechka, Ti Meredith, Craig NVMC needs to decide if we want to continue as a Moore, Tom Taaffe, Celia Zeibel, and Jason Zeibel.
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    Download the Scanned

    682 NOTES AND NEWS atoms are less restricted and their vibrations parallel to the c axis are bigger than those in the (001) plane. Sasset al. (1957) reports a rms dis- placementfor oxygenin CaCOeof about 0.09 A parallel to c which is in good agreement with the value reported in this investigation. Their two anisotropic displacementsin the (001) plane,0.06 A and 0'11 A, re- spectively parallel and perpendicular to the a axis, bracket the value of 0.086 A of Table 2. AcrNowr-npGMENTS The writers wish to expresstheir appreciationto Dr. A. S. Ginzbarg and Miss E. E. Allen who wrote the programsfor the three-dimensional Fourier and least-squarescomputations and to Dr' R. A. Rowland for his critical reading of the manuscript. Rrrnnnmcrs Bnlorev,W. F.,Bunsr, J. l-., eNnGnm, D. L (1953),Crystal Chemistry and Difierential Thermal Efiects of Dolomite: Amer. Mineral.,38,207. Snss, R. L., Vmar.n, R., ero DoNonun, J. (1957), Interatomic Distances and Thermal Anisotropy in Sodium Nitrate and Calcite: Acta Cryst., l0' 567. Wvcrorr, W. G., aNo MnnwtN, H.E. (1924), The Crystal Structure of Dolomite: Amer' J. Sci.,8, M7 . THE AMERICAN MINERALOGIST, VOL. 44, MAY JUNE, 1959 OCCURRENCEOF JORDANITEIN THE OTAVI MOUNTAINS, SOUTHWEST AFRICA N. L. MenrHAM, Grootfontein,Soulh West Afri'ca An interesting occurrence of jordanite (PbrnAszSz+?)has recently been found at Kupferberg in the Otavi Mountains of South West Africa. The following brief note describesits mode of occurrence and chemical composition. The Kupferberg copper prospect lies in the Otavi Valley about 40 miles South West of Grootfontein.