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TGMS General Meeting

  • Tucson Gem and Mineral Society 3727 East Blacklidge Drive Tucson, AZ, 85716 United States (map)

April 1, 2019 TGMS General Meeting

Door will be open at 6:30 p.m. and the meeting will start at 7:00 p.m.

FOR: TGMS Members and open to the public!

Dr. Karen J. Wenrich

Dr. Karen J. Wenrich

GUEST SPEAKER: Dr. Karen J. Wenrich graduated from high school in Wiesbaden, Germany and from Penn State with a B.S., M.S. and a Ph.D. in geology/volcanology.  Karen worked for 25 years for the USGS, followed by a career consulting for the mining industry.  She is a specialist in the geology and mineralogy of uranium deposits.  From 2002-2005 Karen worked for the International Atomic Energy Agency in Vienna, Austria, as their senior uranium geologist in charge of studying uranium resources for the IAEA.  As IAEA staff she shared in their receipt of the 2005 Nobel Peace Prize “ For their efforts to prevent nuclear energy from being used for military purposes.” She has done extensive studies on breccia-pipe uranium deposits in northern Arizona.  In 2008, 2010, and 2011 Karen testified on Capitol Hill before the U.S. House Natural Resources Committee about a proposed bill that would permanently bar the filing of mining claims on 1.1 million acres of federal lands north and south of the Grand Canyon.  These efforts to prevent the bill from passing were successful.  However, subsequently the land was withdrawn via an executive order; she and others are eagerly awaiting a reversal.

LECTURE TITLE: "Mining at the Sweet Home Mine, Alma, Colorado” -- The Sweet Home Mine is nestled at timberline (11,600') near the head of Buckskin Gulch in the Alma Mining District, Mosquito Range, Central Colorado.  The mine's veins lie within Precambrian granite gneiss intruded by Tertiary monzonite porphyry.  Lead-silver mining began in 1872--the mine holds U.S. Patent #106--one of the 1872 Mining Law's oldest.  Like so many of Colorado's old silver mines, the silver-bearing veins were elusive and yielded no bonanza.  However, the tenacity of miners allowed this mine to operate intermittently for over 120 years.  Silver was believed to occur in argentiferous galena, but electron microprobe analyses show little Ag in the galena.  Rather, it occurs in small crystals of stromeyerite, and in other copper sulfides.  The last silver mining occurred in 1966, with little silver production, but with the Alma Queen specimen discovery, which sold for $7,500 in 1966 and was estimated to have a value of $250,000 around 2000, the mine became a target for specimen collectors.  In 1991, Sweet Home Rhodo, Inc. reopened the mine, but silver was hardly the target--instead, cherry-pink, gemmy rhodochrosite was the commodity of interest.  In 1992 they struck the Good Luck Pocket, which included "museum grade" rhodochrosite along with fluorite, tetrahedrite, sphalerite, and hübnerite.  The mining operation continued to be a success until the mine closed in 2004.  The Sweet Home Mine has produced millions of dollars in mineral specimens since 1991--a far better bonanza than was ever reaped by silver production.

Refreshments served.

For more information, contact the TGMS office.

Earlier Event: February 14
Tucson Gem & Mineral Society presents ...
Later Event: April 5
2019 Minerals of Arizona Symposium