Montana designated both the sapphire and Montana Agate as the official state gemstones in 1969. Agates are found in southern and eastern Montana. Agate is polished (not cut) to make gemstones and jewelry. Agates are usually white with swirls of grey and black spots.
The Montana Council of Rock and Mineral Clubs asked the legislature to declare both the sapphire and the Montana agate (agate is found in abundance along the Yellowstone River) as Montana’s official state gemstones.