Chrysocolla is a basic copper silicate composed of a mix of various microscopic crystals found in a variety of colors. It has a greasy vitreous luster. The name chrysocolla originated in ancient times, and was applied by the Greek philosopher Theophrastus in 315 BC to various materials used in soldering gold. The name is derived from the Greek chrysos, meaning gold, and kolla, meaning glue. It is a minor ore of copper and is used as an ornamental stone.
Chrysocolla is harder than turquoise and softer than chalcedony. It is a secondary mineral and usually forms in the zone of alteration in all types of hydrothermal replacement deposits, where it is frequently associated with azurite, malachite and limonite. Chrysocolla is soft and fragile and tends to break easily when exposed to the atmosphere. It is mixed with quartz or chalcedony to give it durability.
Chrysocolla is frequently inter-grown with other minerals such as quartz, chalcedony, or opal to yield a harder, more resilient gemstone variety. Inter-grown with turquoise and malachite from Israel it is called “Eilat stone,” which is the national stone of Israel. In 1950, the United States’ lapidaries voted chrysocolla-colored chalcedony the “most popular American gem.”
Most chrysocolla comes from the southwest United States, but it is also found at Cornwall, Lebanon Co., Pennsylvania. Fine specimens of glassy green chrysocolla were also obtained from copper mines at Bisbee, Cochise Co., in the Globe district, Gila Co., and in the Clifton-Morenci district, Greenlee Co., all in Arizona.
Chrysocolla is usually confused with azurite, dyed chalcedony, malachite, turquoise, and variscite.