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Covellite
Current inventory:  0 gems
 

Chemistry:  CuS

Discovered in 1832;   IMA status: Valid (pre-IMA; Grandfathered).
Covellite, also known as Covelline, is named after N. Covelli (1790-1829), an Italian mineralogist and discoverer of the mineral at Mount Vesuvius.

Classification

Mineral Classification:

Sulphides

Strunz 8th Ed. ID:

2/C.22-10

2 : Sulphides
C : Sulphides with metal: sulphur, selenium and tellurium = 1:1
22 : Covellite series

Crystal Data

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

Physical Properties

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

Optical Properties

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

Occurances

Geological Setting:

Most commonly of secondary origin in the zone of oxidation in sulfide copper deposits. Rarely of primary hydrothermal origin. Widespread in most copper deposits; common as an iridescent tarnish on other sulfides.

Type Locality:

Mt. Vesuvius, Somma-Vesuvius Complex, Naples Province, Campania, Italy

Year Discovered:

1832

View mineral photos:

Covellite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Covellite is a little known sulphide mineral in the gem world but one look at its metallic luster, iridescent, deep indigo blue color with purplish, deep red and brassy-yellow reflections would make just about anyone a fan of this rare and beautiful gem. Covellite is always opaque, so it is only available as cabochons. But Covellite has perfect, leafy cleavage so even cabochons are rare.

Covellite is found in a few locations worldwide but fine crystals are rare. The most notable occurances are Mt. Vesuvius, Campania, and Calabona mine, Alghero, Sardinia, Italy; Butte, Silver Bow Co., Montana, USA as fine crystals in the primary ore; and at the Galactic Open Pit, Summitville, Summit District, Rio Grande Co., Colorado, USA.
 

  
Covellite gems for sale:

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