Formula: CuS,  (Cu⁺)₃(S^2-)(S₂)^–.

Species:

Colour: Indigo-blue or darker, inclining towards blue-black, often iridescent with purplish, deep red, and brassy-yellow reflections.

Lustre: Sub-Metallic

Hardness: 1½ – 2

Specific Gravity: 4.6 – 4.76

Crystal System: Hexagonal

Name: Named in 1832 by Francois Sulpice Beudant in honor of Niccolo Covelli (1790-1829), an Italian mineralogist and discoverer of the mineral at Mount Vesuvius.

Type Locality: Mount Vesuvius, Somma-Vesuvius Complex, Naples, Campania, Italy

Usually as indigo-blue massive metallic material, sometimes with crystals on exposed surfaces (those often spheroidal). Good crystals extremely rare.