What is "terlinguaite"

n. (context mineralogy English) A monoclinic-prismatic mineral containing chlorine, mercury, and oxygen.

Terlinguaite is the naturally occurring mineral with formula Hg Cl O. It is formed by the weathering of other mercury-containing minerals. Discovered in 1900 in the Terlingua District of Brewster County, Texas for which it is named. Its color is yellow, greenish yellow, brown or olive green.