Posted on May 09, 2019 by Mary Hood | 0 Comments
More gem-quality sapphires are produced in Montana than any state in the United States. Montana sapphires (or corundums) come in a variety of colors (although rubies are rare).
The first sapphire found in the U.S. was found along the Missouri River by Ed “Sapphire” Collins in 1865. Other areas along the Missouri River in Montana, including Butte, Philipsburg, and Bozeman, have also produced sapphires. Some of the first sapphire finds were deemed low-quality, however, giving Montana sapphires a bad reputation. Because of their poor color quality and lack of clarity, many Montana sapphires are treated with heat to enhance their color and clarity (a general trend that does not apply to Yogo sapphires, discussed below).
Raw Montana Sapphire
Due to environmental concerns, high cost of recovery, and low-profit margins of general-variety, non-blue Montana sapphire, not many are mined today.
Yogo sapphires are found only in the Yogo Gulch, part of the Little Belt Mountains in Judith Basin County, Montana. The land was once inhabited by the Piegan Blackfeet Native Americans, and it’s speculated that “yogo” means “romance” or “blue sky” in the Blackfeet language, but no one is quite sure.
Purple Yogo Sapphire
Yogo sapphires are celebrated for their uniform clarity and brilliance. Trace amounts of iron and titanium render most yogo sapphires a beautiful cornflower blue (though about 2% of yogo sapphires are purple.
The first gold discovery at Yogo Creek occurred in 1866, at which point miners found “blue pebbles,” but these stones weren’t recognized as sapphires until 1894. In 1895, rancher Jake Hoover sent a cigar box full of these rocks to an assay office that sent it to Tiffany’s in New York City where these gems were declared “the finest precious gemstones found in the United Stated.” The discovery of Yogo sapphires was arguably more valuable than several gold strikes.
The allure of Yogo sapphires endured through the twentieth century. In the 1980s, gem company Intergem (which controlled most of the Yogo sapphires at the time), declared that Yogo sapphires were the world’s only guaranteed “untreated” sapphire, drawing attention to the fact that by that point, 95% of the world’s sapphires were treated to enhance color and clarity (the context of that figure is rather complicated, however, and sapphires can be treated in more than one way).
The life-size Tiffany Iris Brooch, contains 120 Yogo sapphires set in platinum (circa 1900).
Although Yogo sapphires continue to be valuable, the difficulty of mining them makes them expensive to produce and therefore less profitable than equally valuable gems that are easier to mine. These days, Yogo sapphire mining is mostly practiced by hobbyists, and most of the larger mines are inactive.
Photos: Wikimedia Commons