paratacamite
/ˌparətəˈkɑːmʌɪt/Mineralogy
noun
A green to greenish-black mineral of the hexagonal system that consists of a basic chloride of copper, Cu2(OH)3Cl, and is found as a secondary deposit on other copper minerals.
Origin
Early 20th century; earliest use found in Nature: a weekly journal of science. From para- + atacamite: see quot. 1907, which reports a talk given in 1905.