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Covellite

Discovered in 1832; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

CuS

Copper Sulphide

Molecular Weight:

95.61 gm

Composition:

Copper

66.46 %

Cu

Sulfur

33.54 %

S

100.00 %

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

Varieties:

Argentian Covellite, Selenian Covellite

Synonyms:

Blue Copper, Breithauptite (of Chapman), Copper Indigo, Covelline, Covellinite, Covellonite

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.

Common Associations:

Bornite, Calcite, Chalcocite, Chalcopyrite, Malachite, Marcasite, Plumosite, Pyrite, Quartz, Sulphur

Common Impurities:

Fe, Se, Ag, Pb

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 somewhat rare copper sulphide mineral that is available as opaque cabochons with beautiful metallic luster, deep indigo blue color with purplish and brassy-yellow reflections.

Covellite was named in 1832 by French mineralogist Francois Sulpice Beudant (1787 - 1850) in honor of Italian mineralogist Niccolo Covelli (1790 - 1829), the discoverer of the mineral at Mount Vesuvius.

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 County, Montana, USA as fine crystals in the primary ore; and at the Galactic Open Pit, Summitville, Summit District, Rio Grande County, Colorado, USA.

Covellite gems for sale:

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