BLUE AGATE (BLUE CHALCEDONY), Nebraska State Gemstone
On March 1, 1967, Nebraska's centennial, Governor Norbert T. Tiemann signed a bill designating blue chalcedony, commonly called the blue agate, as Nebraska's official state gemstone. A pale stone, blue chalcedony may consist of a crystal internal form surrounded with blue, white, and often colorless bands. Classified as a semiprecious stone, it is frequently used to make jewelry. Blue agates are found in northwest Nebraska in the Chadron Formation. Agates formed in wind-blown silt and claystone deposited more than twenty-five million years ago.