Clint and Louisa Cross, partnering with Australians Graham and Anna Slater. Clint, a Native American member of the Sokoki Tribe of the Abenaki Nation of Mis- sisquoi, started as a gold prospector 25 years ago.The Cripple Creek region lies in what is known as the Thirtynine Mile volcanic area, which yields numerous calderas, one of which Clint Cross discov- ered.A caldera, in simple terms, is a collapsed volcanic dome. The experts, upon examination of this Turquoise from the North Star property, note that it contains a high silica property, making it significantly more durable and higher in hardness than material found in other Turquoise mine sites in the Unit- ed States and other localities in the world. North Star Turquoise requires no stabiliza- tion. North Star is the only commercially active Turquoise mine in Colorado and a rare source for natural, untreated Turquoise. Montana is known as the “Treasure State” due to its resources of Sapphires, platinum, copper, gold and other metals. Montana Sap- phire is not a recent discovery; deposits have been mined for more than 120 years. It has only been since 2015 that the area has been returned to large-scale commercial mining by Potentate Mining LLC, a Montana com- pany. Potentate owns more than 3,000 acres of private property, covering about 90% of the known Sapphire producing ground at Rock Creek. The Rock Creek Sapphire ™ mine is the largest producer of Sapphires in America and is located near the silver mining town of Philipsburg in the Sapphire Mountains. The Sapphires are mined from the top of the mountain and the source rocks, Potentate Mining LLC: Philipsburg, Montana possibly alkali basalt, are entirely weathered away, leaving the Sapphires and other resis- tant minerals.The mining is of the weath- ered surface gravels, called eluvium, so no deep pits or underground mining is required. Rock Creek is a famous Blue Ribbon trout stream and Potentate takes their envi- ronmental responsibilities very seriously by ensuring no muddy water is released into the environment and all disturbed ground is fully rehabilitated under Montana’s Department of Environmental Quality guidelines. Potentate uses no chemicals in the recovery process, and all water used in the plant is contained in a closed-loop and fully recycled. A small percentage of the Rock Creek Saphires ™ does not require any form of treatment; these gemstones are quite rare. The balance of the gem-quality Sapphire may contain small amounts of rutile (TiO2) within the crystal structure that reduces
the clarity of the gem and thus these are heat treated. Innovative heat treatment technology for Rock Creek Sapphire™ was only developed in the 1990s.This heat treatment technology—performed in Montana—in- volves oxidizing and reducing atmospheres in sophisticated ovens which dissolve the rutile, allowing the titanium to enter the crystallographic matrix.This improves the clarity and intensity of the color saturation. The most common Rock Creek Sapphire™ colors are blue, blue-green, teals, and greens with rare colors of yellow, orange, lavender, colorless, and padparadscha.
Top down: LoneMountain polished Turquoise nuggets. P hoto courtesy of LoneMountainMining LLC. A premium selection of both natural and heat-treated polished Rock Creek Sapphire ™ showing the diversity of colors with sizes ranging from0.49 to 4.19 carats. Photo courtesy of Jeff Hapeman. Part of themining operation of Rock Creek Sapphires™ at the top of themountain. Photo courtesy of PotentateMining.
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