Chalcanthite is a rare mineral due to being a water-soluble sulphate. It is a secondary blue-colored mineral formed in arid climates or in rapidly oxidizing copper deposits. It usually forms post-mining, crystallizing on mine walls and by the action of acidic surface waters on copper veins. It was discovered in 1853 at the Chuquicamata Mine, Chile, where it is an important ore mineral. It is named from two Greek words meaning "brass/copper" and "flower."

Mineral Photos courtesy of R.Weller/Cochise College