Montana’s most popular gemstone product is sapphire. Yogo Gulch sapphires have been famous for over 100 years, and the production of sapphires in Montana continues today. Sapphires are produced from both rock and alluvial deposits. They occur in a wide range of colors which include blue, blue-green, green, pink, pale red, purple, yellow, and orange (colors often produced by heat treatment). Some gem-grade garnets are also produced from the alluvial deposits.

Rockhounds in many parts of Montana enjoy looking for agate and jasper. One of the most popular is “Montana Moss Agate,” a transparent to translucent material that usually has brown to black bands or “moss” in a wide variety of patterns.