Chemical Formula: CuS
Locality: Monte Somma, Vesuvius, Naples, Naples province, Campania, Italy.
Name Origin: Named after the Italian mineralogist, N. Covelli (1790-1829).
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).
Physical Properties
Cleavage: {0001} Perfect
Color: Indigo blue, Light blue, Dark blue, Black.
Density: 4.6 – 4.76, Average = 4.68
Diaphaneity: Opaque
Fracture: Brittle – Generally displayed by glasses and most non-metallic minerals.
Hardness: 1.5-2 – Talc-Gypsum
Luminescence: Non-fluorescent.
Luster: Metallic
Magnetism: Nonmagnetic
Streak: black gray
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