233-249.The Benitoite Gem mine was referred to as the “Dallas mine” until the mid-1960s, but it has been variously called the “Benitoite mine,” “Dallas Benitoite mine”, and “Dallas Gem mine” (Wise and Gill, 1977). 5, pp. From shop GeminiMinerals. Dispersion is the splitting up of white light into its individual wavelengths, what we see as colors. The natrolite veins average less than 1 cm wide, and contain benitoite only locally, commonly where the veins narrow or terminate. California State Gem Mine (Benitoite Gem Mine), San Benito River headwaters area, Santa Rita Peak, New Idria District, San Benito County, California USA Specimen size: 1.7 × … During the 1940’s, Mr. M. Hotchkiss used a bulldozer to enlarge the open cuts at the top of the hill. The mine produced benitoite from an open cut in the hillside, as well as a short underground tunnel pushed into an outcrop of benitoite-bearing material called blueschist. BMI then rehabilitated the site. Hundreds of feet of diamond drilling and dozens of test pits proved the existence of economical gemstone reserves.Hinthome J.R. (1974) The origin of sanbornite and related minerals. Fortunately, the natrolite coatings protect the benitoite and neptunite crystals on the specimens from damage during the mining and screening operations.Rohtert W.R. (1994) Preliminary geologic map of the Benitoite Gem mine.
U.S. Geological Survey Open File Map 79-358, scale l:125,000.In 1912, the market for Benitoite slackened and, coming upon difficult financial times, Mr. Dallas closed the mine. Mineral News, Vol. 418-510.Benitoite has been confirmed from several locations around the world, but gem quality crystals have only been found at the historic Dallas claim (popularly known as the “Benitoite Gem mine”) and the nearby Junnila claim, both located in the New Idria district, San Benito County, California. 166-187, Fall 1997Benitoite Mining, Inc. (BMI), a company affiliated with Collector’s Edge Minerals, Inc., headquartered in Golden, Colorado, operated the mine until 2004, selling it in 2005 to Dave Schreiner of Coalinga, California. 5, p. 5.When word got out of the new discovery, several people, including Dr. George Kunz from Tiffany’s of New York, rushed to the site to secure an exclusive marketing agreement with the miners. American Mineralogist, Vol.
It has a high index of refraction and a dispersive power that is higher than diamond, making the stone extraordinarily bright and fiery when cut. This map is found in a Gems & Gemology article, Vol.
The other crystal, even larger, 2.2 cm by approximately 1.7 cm tall, by 8.5 mm thick.
This plate sold in Tucson 2012 for 5 figures.If you are not a rockhound, mineral collector, or connoisseur of rare gemstones, then you may have never heard of Benitoite.Enter your e-mail address to receive our newsletter.With the color of the most valuable tanzanite, it is easy to see why it is so valued.
Ph.D. dissertation, University of California at Santa Barbara.que qualities compared to other gems. When open spaces occur, allowing for the formation of crystal faces, the form of the aggregates are certainly not typical of natrolite. Four other benitoite prospects in the district are claimed as follows: (1) The Junnila claim; (2) The Mina Numero Uno claim; (3) The Victor claim; and (4) The Santa Rita Peak property. We specialize in […]A further refinement was implemented to improve gem recovery.
Get the best deals on Benitoite Other Loose Gemstones when you shop the largest online selection at eBay.com. Neptunite occasionally forms crossing twins, similar to staurolite, with the angle between the c-axis near 40 degrees.Collector’s Edge Minerals, Inc. recognizes and thanks the Mineralogical Record for permission to use portions or all of their original […]During the period of CEMI activities (2000-2004), approximately 30,000 yards of material, including existing dump material of about 20,000 yards, were processed.