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NVMC Newsletter 2016-10.Pdf The Mineral Newsletter Meeting: October 24 Time: 7:45 p.m. Long Branch Nature Center, 625 S. Carlin Springs Rd., Arlington, VA 22204 Volume 57, No. 8 October 2016 Explore our Website! October Program: Geologic History of the Valley and Ridge In this issue … Mineral of the month: Spessartine..................................... p. 2 October program details ..................................................... p. 3 The Prez Sez ........................................................................ p. 3 September meeting ............................................................ p. 4 Club officer elections coming up ........................................ p. 4 Holiday party coming up ..................................................... p. 5 25th Annual Mineral Show—Volunteers needed!! ............ p. 6 Sad news about Fred Schaefermeyer ................................. p. 8 Road trip coming up ............................................................ p. 9 EFMLS: Safety matters ........................................................ p. 9 AFMS: Code of Ethics .......................................................... p. 10 The Estes Quarry in Maine .................................................. p. 11 Webelos Scouts learn geology ............................................ p. 12 African stone types ............................................................. p. 13 Upcoming events ................................................................ p. 15 Spessartine Smithsonian National Mineral Collection. Photo: Chip Clark. garnet on muscovite Mineral of the Month Spessartine by Sue Marcus Lovely spessartine can’t seem to keep a name. This member of the garnet family was always known from Northern Virginia Mineral Club the Spessart Mountains of Germany, although Martin Klaproth originally named it granatförmiges Braun- members, steinerz (“granite-shaped manganese ore”) in 1797. Please join our October speaker, Professor Shelley Jaye, The name became “manganesian garnet” in 1823 be- for dinner at the Olive Garden on October 24 at 6 p.m. fore François Sulpice Beudant, in 1832, bestowed its current name of spessartine, for the original locality. Olive Garden, Baileys Cross Roads (across from Skyline Spessartine can be found in all major rock types—in Towers), 3548 South Jefferson St. metamorphic and igneous rocks as a primary mineral. (intersecting Leesburg Pike), In sedimentary rocks, it erodes from the other rock Falls Church, VA types and is deposited in the sediments. Phone: 703-671-7507 As part of the Garnet Group, spessartine shares ele- Reservations are under Ti Meredith, Vice-President, ments with a spectrum of others in the group, such as pyrope and almandine. All may form gem-quality NVMC. Please RSVP to me at [email protected]. materials. A mixture of pyrope and spessartine called Malaya garnet (an unofficial name), from Tanzania and Kenya, is used in jewelry. Malaya garnets occur in unique and rare colors, like pink-orange, red- the wimpy route—you may have found something orange, and yellow-orange. new for your locality, though getting it verified as Sylvanite A different rare hybrid of spessartine and pyrope is such may be difficult. from Romania reported by gemselect.com. This variant changes col- Technical details (source mostly Mindat (2016)): or, depending on the light source. The hybrid is not 2+ Silver‒gold telluride Chemical formula ......... Mn3 Al2(SiO4)3 (good luck truly pleochroic, because “pleochroic” applies only to printing that one!) (Ag,Au)Te2 doubly refractive minerals and these garnets are sin- Crystal form .................. Isometric gly refractive. Hardness ...................... 6.5–7.5 China has been a recent source of beautiful spessar- Density .......................... 4.12–4.32 g/cm3 (measured) tine specimens. The bright orange-red spessartine Color ............................. Usually deep or dark red, to crystals stand out against white albite. The pegmatites slightly purplish red, brown, less frequently orange of Afghanistan, Brazil, and Pakistan are also signifi- Streak ............................ White cant spessartine producers. An orange variant is Cleavage ........................ None found in Madagascar; closer to home, violet-red spes- Fracture ......................... Subconchoidal sartines come from Colorado and Maine. San Diego County, CA, has been the main spessartine producer Luster ............................ Vitreous in the United States, with an estimated 40,000 to While looking at sources for this article, I noticed that 50,000 carets of faceting-grade rough material mined even high-level dealers like John Betts listed many of between 1956 and 1994. the garnet specimens as “Almandine-Spessartine,” A challenge for collectors is knowing when the garnet presumably because it was somewhere along that part you found is spessartine. It is usually impossible to of the Garnet Group spectrum. Garnets are relatively tell without extensive and often expensive analysis. easy and fun to fine, so happy and safe collecting! My rule of thumb—and it is no more than that—is to Sources find well-referenced literature on the collecting lo- cality and go with what is given there. That may be GemSelect. 2016. Spessartite garnet gemstone infor- mation. The Mineral Newsletter October 2016 2 GemSelect. 2016. Pleochroic gemstones. Laurs, B.M.; Knox, K. 2001. Spessartine garnet from Smithsonian Photos Have Changed Ramona, San Diego County, CA. Gems and Gem- Hutch Brown, Editor ology 37(4). Mindat. 2016. Spessartine. Cover photos for The Mineral Newsletter typically Minerals.net. 2016. The mineral spessartine. show specimens in the Smithsonian National Min- Wikipedia. 2016. Spessartine. eral Collection. In case you wondered, the Smith- sonian has revised its online collection of photos; the photo on page 1, for example, is no longer in The Geologic History of the Valley and the online Smithsonian Mineral Gallery. Ridge (as Recorded in the Rocks of The Smithsonian might be simply updating its rec- Corridor H, WV) ords. George Loud pointed out that “the Smithson- October 24 Program ian stibnite shown on page 1 of the May newsletter is the same specimen pictured on a Smithsonian Please join Professor Shelley Jaye for a fascinating postcard, which no longer exists (it was dropped exploration of the geologic history of the Valley and and shattered).” The lost stibnite is shown below. Ridge Province, as exposed in the rocks of Corridor H in West Virginia. If you’ve missed Shelley’s field trips along the corridor, here’s your chance! Shelley began her exploration of the geosciences at a community college in suburban Detroit, MI. She at- tended Wayne State University in downtown Detroit, where she received both her B.S. and her M.S. de- grees in geology. She conducted field research study- ing early Paleozoic metasediments and metavolcanics on the island of Spitsbergen in the Svalbard archipel- ago, north of Norway. After graduating, she took a position with the U.S. government as a program manager in what is now the National Geospatial Intelligence Agency. That career was exciting and rewarding but also stressful and time intensive. By the late 1990s, with two small children, Shelley The Prez Sez decided to change careers. She began teaching Earth Science at Potomac Falls High School in Sterling, by Bob Cooke VA. After a move to the Norfolk, VA, area, Shelley began teaching geology at Tidewater Community We’re in the final countdown. The College. One step back into the community college club’s 25th Annual Gem, Mineral, and environment and she knew that she found the perfect Fossil Show is almost upon us! Please, second career. please, please sign up to volunteer at: Shelley is now at the Annandale Campus of Northern http://signup.com/go/RzFiiS. Virginia Community College teaching mineralogy as This show is the one fundraiser that provides the well as physical and historical geology. She is always monies for all other NVMC activities. We need it to trying to find opportunities for students to conduct come off without a hitch. And this year we’re without real research. some of the key personnel we had in prior years. Do I sound desperate, frantic and worried? I am. We need Note: To avoid any conflict with Thanksgiving, everyone to pitch in! next month’s meeting will be on November 14. Mark your calendar! The Mineral Newsletter October 2016 3 In addition to the Mineral Show in November, we have lots of other club activities. There’s a field trip to the Vulcan quarry in Manassas on the October 15; CLUB OFFICER ELECTIONS and we’re invited to a GLMS-MC field trip to the COMING UP! National Limestone Quarry on October 29. The October meeting will feature a presentation by Professor Shelley Jaye on the geologic history of the It’s that time of year again! Valley and Ridge, as displayed along Corridor H in At the December club meeting, we will elect West Virginia. With a little luck, we will get Shelley club officers for 2017. We need candidates to lead us on a field trip to this area, which is only 2 for president, vice-president, secretary, and hours away. She can explain firsthand the complex rock strata shown in roadcuts, documenting the as- treasurer. sembly of the Pangaea supercontinent (the mountain- As chair of the nominating committee, I am building event that created the Appalachian Moun- asking club members to step forward to help. tains) as well as the ultimate breakup of Pangaea. We need a mix of long-term club members and newer members in officer positions so we can both offer
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