Montana
Although sapphires can be found throughout Montana, the majority of the finds can be attributed to four major locales: Yogo Gulch, Rock Creek, Dry Cottonwood Creek, and the gravel bars along the Missouri River northeast of Helena.The Missouri River, Rock Creek, and Dry Cottonwood Creek deposits are associated with high yields of high-clarity fancy sapphires, with colors ranging from light pinks, purples, oranges, yellows, and greens, to pale blues.
map-of-montana
Sapphire production in Montana was, at least initially, a byproduct of the gold rushes of the 1860s. Early prospectors searching for gold in the gravel of the Missouri River discarded the annoying blue pebbles that continually clogged their sluices. The discovery that these stones had value is attributed to Ed “Sapphire” Collins who forwarded samples to Tiffany and Company in 1865.When Tiffany purchased the lot for $3,750 and declared that the stones were “sapphires of unusual quality,” a small scale sapphire rush began. A year later, the source of the sapphires, an igneous dike about five miles in length, was discovered by a part-time prospector and sheep farmer, John Ettien. The “cornflower blues” of Yogo Gulch attracted considerable attention and funding from both domestic and foreign mining companies. A British company controlled the mine for some thirty years, which is why Yogo sapphires can be found among the British Crown Jewels.
Untreated Yogo sapphires are famous for their excellent blue color and exceptional clarity; and many believe their natural qualities surpass heat-treated stones from all over the world. However, their primary drawback is their small size. Cut gems from Yogo Gulch are very rarely more than one carat in size.
