What is "covellite"

Covelline \Co*vel"line\ (k?-v?l"l?n), Covellite \Co*vel"lite\ (-l?t), n. [After Covelli, the discoverer.] (Min.) A native sulphide of copper, occuring in masses of a dark blue color; -- hence called indigo copper.

n. (context mineral English) A shiny indigo-blue sulfide mineral, coppersulfur, that is an ore of copper.

Covellite (also known as covelline) is a rare copper sulfide mineral with the formula CuS. This indigo blue mineral is ubiquitous in copper ores, it is found in limited abundance and is not an important ore of copper itself, although it is well known to mineral collectors.

The mineral is associated with chalcocite in zones of secondary enrichment ( supergene) of copper sulfide deposits. Commonly found with and as coatings on chalcocite, chalcopyrite, bornite, enargite, pyrite, and other sulfides, it often occurs as pseudomorphic replacements after other minerals. Despite the very rare occurrence as a volcanic sublimate, the initial description was at Mount Vesuvius by Nicola Covelli (1790–1829).