Yogo Sapphires : The ‘Blue Pebbles’ of Montana
Yogo sapphires or Montana sapphires are blue sapphires, a colored variety of corundum, found in Montana, primarily in Yogo Gulch (part of the Little Belt Mountains) in Judith Basin County, Montana. Yogo sapphires are typically cornflower blue, a result of trace amounts of iron and titanium. They have high uniform clarity and maintain their brilliance under artificial light. Because Yogo sapphires occur within a vertically dipping resistive igneous dike, mining efforts have been sporadic and rarely profitable. It is estimated that at least 28 million carats (5.6 t or 5.5 long tons or 6.2 short tons) of Yogo sapphires are still in the ground. Jewelry containing Yogo sapphires was given to First Ladies Florence Harding and Bess Truman; in addition,...
