Rock Creek Sapphires

The Origin of Montana’s Alluvial Sapphires

Another spotlight for Potentate in the prestigious ‘Gems and Gemology’ publication from the Gemmological Association of Great Britain (GemA) – the oldest Gemmological Association in the world.   Peer Reviewed Article by J.C. (Hanco) Zwaan, Eric Buter, Regina Mertz-Kraus, and Robert E. Kane

Although the source rocks of alluvial sapphires in Montana have never been discovered, inclusions and geochemistry of material from this location may give clues to their original source. Mineral inclusions in alluvial Montana sapphires, mainly from Rock Creek, were identified and compared with existing data. Topaz was a remarkable find in one of these samples; other newly identified mineral inclusions in Montana sapphire were allanite, anatase, chalcopyrite, and monazite.

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