Covellite
Covellite (also known as covelline) is a rare copper sulfide mineral with the formula CuS. This indigo blue mineral is commonly a secondary mineral in limited abundance and although it is not an important ore of copper itself, it is well known to mineral collectors.
| Covellite | |
|---|---|
| General | |
| Category | Sulfide mineral |
| Formula (repeating unit) | CuS (copper monosulfide) |
| IMA symbol | Cv |
| Strunz classification | 2.CA.05a |
| Dana classification | 02.08.12.01 |
| Crystal system | Hexagonal |
| Crystal class | Dihexagonal dipyramidal (6/mmm) H–M Symbol (6/m 2/m 2/m) |
| Space group | P63/mmc |
| Unit cell | a = 3.7938 Å, c = 16.341 Å; Z = 6 |
| Identification | |
| Color | Indigo-blue or darker, commonly highly iridescent, brass-yellow to deep red |
| Crystal habit | Thin platy hexagonal crystals and rosettes also massive to granular. |
| Cleavage | Perfect on {0001} |
| Tenacity | Flexible |
| Mohs scale hardness | 1.5–2 |
| Luster | Submetallic, inclining to resinous to dull |
| Streak | Lead gray |
| Diaphaneity | Opaque |
| Specific gravity | 4.6–4.8 |
| Optical properties | Uniaxial (+) |
| Refractive index | nω = 1.450 nε = 2.620 |
| Pleochroism | Marked, deep blue to pale blue |
| Fusibility | 2.5 |
| Other characteristics | Micaceous cleavage |
| References | |
The mineral is generally found in zones of secondary enrichment (supergene) of copper sulfide deposits. Commonly found as coatings on chalcocite, chalcopyrite, bornite, enargite, pyrite, and other sulfides, it often occurs as pseudomorphic replacements of other minerals. The first records are from Mount Vesuvius, formally named in 1832 after N. Covelli.
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