Covellite
Covellite is a little known sulphide mineral in the gem world but one examine its metallic luster, iridescent, deep indigo blue color with purplish, deep red and brassy-yellow reflections would make just about anyone a fan with this rare and gem that is beautiful. Covellite is often opaque, it is therefore just available as cabochons. But Covellite has perfect, leafy cleavage so even cabochons are rare.
Covellite can be found in areas which are few but fine crystals are uncommon. The most occurances that are notable Mt. Vesuvius, Campania, and Calabona mine, Alghero, Sardinia, Italy; Butte, Silver Bow Co., Montana, USA as fine crystals in the ore that is main and at the Galactic Open Pit, Summitville, Summit District, Rio Grande Co., Colorado, United States Of America.
| Category | Sulfide mineral |
| Formula: | copper sulfide:CuS |
| Crystallography: | Hexagonal – Dihexagonal Dipyramidal |
| Crystal Habit: | Forms hexagonal plates as large as 10 cm, flattened on [0001], which may exhibit hexagonal striae; as rosettes of nearly parallel plates; commonly massive and foliated. |
| Twinning: | None reported |
| Cleavage: | [0001] Perfect |
| Fracture: | Irregular, Uneven, Hackly, Flaky |
| Tenacity: | Flexible in thin leaves |
| Hardness (Moh’s): | 1.5 – 2.0 VHN100=128 – 138 kg/mm2 |
| Hardness (Vickers): | VHN100=128 – 138 kg/mm2 |
| Density: | 4.60 – 4.76 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Other: | Nonmagnetic |
| Color: | Deep, metallic, Indigo-blue, inclining towards blue-black, often iridescent with purplish, deep red, and brassy-yellow reflections. |
| Transparency: | Opaque |
| Luster: | Metallic, Submetallic, inclining to resinous, somewhat pearly on cleavage; subresinous to dull when massive. |
| Refractive Index: | 1.450 – 2.620 Uniaxial ( + ) |
| Birefringence: | 1.170 |
| Dispersion: | Strong |
| Pleochroism: | Visible; deep blue to blue-white |
| Anisotropism: | Strong |
