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Montana Sapphires
Chip Clark
Specimen | Catalog Number | Locality | Weight |
---|---|---|---|
Corundum (var. sapphire) | NMNH G3365 | United States, Montana | 153.20 ct |
Gift of Smithsonian Gem and Mineral Collectors in 1961.
This colorful assortment of sapphires was recovered from the gravels of the Missouri River bars near Helena, Montana. They range from about 0.1 to 2.5 carats.Sapphires are a variety of the mineral corundum. Pure corundum is colorless, but chemical impurities in the crystal structure can impart a range of vivid colors. Although commonly thought of as blue gems, sapphires exist in a variety of colors as seen here. Iron and titanium are responsible for the blue color of sapphires. Sapphires other than blue are called "fancy-colored" and range from pink, yellow, and orange to purple, green, and even black.