What is the origin of 'sleep tight'?
Read moreOne of the mysteries of the English language finally explained.
An earthy impure black oxide of copper; a form of tenorite containing hydrated copper silicate and carbonate.
Mid 19th century; earliest use found in James Dana (1813–1895), geologist, zoologist, and teacher. Alteration of melaconise after -ite; compare conite.