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These rough nodules (up to 4+ grams) and faceted stones (3.31 and 4.21 ct) show the range of color of demantoid from the Kladovka mine. Photo © Jeff Scovil.
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At the AGTA show, Bill Larson of Pala International, Fallbrook, California, had large quantities of rough and fine cut demantoid garnets from a recently rediscov ered primary deposit in the historic Sissertsk district in the Ural Mountains. The Kladovka mine is located about 10 km from the city of Kladovka, which is a two-hour drive south of Ekaterinburg. In the past, primary deposits in this area produced mostly mineral specimens, while nearby placers yielded significant amounts of gem rough (W. R. Phillips and A. S. Talantsev, “Russian demantoid, czar of the garnet family,” Summer 1996 Gems & Gemology, pp. 100–111).
Mr. Larson and his partner, Nicolai Kuznetsov of Moscow-based Stone Flower Co., helped fund an Ekaterinburg team of prospectors who began exploring the area in May 2002 after researching the historic localities of this czarist gem, first discovered in Russia in the mid-19th century. By July 2002, the prospectors were on the verge of abandoning their search in the heavily forested area when they rediscovered an old mining pit and exposed a “vein” containing demantoid. The garnets formed rounded nodules and aggregates along this vertical horizon in the sheared serpentinite host rock, which varied from a few centimeters up to 50 cm wide.
According to Mr. Larson, Pala International has obtained 8.3 kg of rough of variable color, from yellowish or brownish green to bright green. Approximately 600 grams is of top cutting grade. A significant portion will cut stones exceeding 1 ct each; however, gems over three carats (see, e.g., figure) are very rare. The largest gem faceted so far weighed 6.71 ct. “Horsetail” inclusions are present in some of the material.
The demantoid was produced from a pit measuring about 500 x 200 m and up to 12 m deep, which was excavated from the low hillside using backhoes and manual labor. A pump is used to remove water from the pit. The mining season lasts just four to six months, and as many as six miners worked the pit this past summer. Depending on the weather, this year’s season should start in May.
Mr. Larson indicated that unlike the demantoid from the Karkodino mine (also in the Ural Mountains)—much of which is treated by a simple heating process to remove the brownish color component—the material from Kladovka has not been treated in any way. For more information on the Kladovka demantoid, visit the Web site www.palagems.com/demantoid_garnet.htm.
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