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Cubanite
Current inventory:  1 gem
 

Chemistry:  CuFe₂S₃  [Copper Iron Sulfide]

Discovered in 1843;   IMA status: Valid (pre-IMA; Grandfathered).
Cubanite is named for its discovery in Cuba.

Classification

Mineral Classification:

Sulfides

Strunz 8th Ed. ID:

2/C.14-20

Nickel-Strunz 10th Ed. ID:

2.CB.55a

2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
C : Metal Sulfides, M: S = 1: 1 (and similar)
B : With Zn, Fe, Cu, Ag, etc.

Related to:

Cubanite Series. Dimorph of Isocubanite.

Crystal Data

Crystallography:

Orthorhombic - Dipyramidal

Crystal Habit:

Crystals thick tabular; striated, to 3 cm; also massive.

Twinning:

Common with twin plane [110], in pairs, also as fourlings and sixlings; then pseudohexagonal.

Physical Properties

Cleavage:

None; Parting on [110] and [130]

Fracture:

Conchoidal

Tenacity:

Brittle

Hardness (Mohs):

3.5

Density:

4.03 - 4.18 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Other:

Strongly magnetic

Optical Properties

Color:

Brass Yellow, Bronze Yellow

Transparency:

Opaque

Luster:

Metallic

Refractive Index:

n/a  (Opaque)

Birefringence:

n/a  (Opaque)

Dispersion:

n/a  (Opaque)

Pleochroism:

n/a  (Opaque)

Anisotrophism:

Distinctive on polished surfaces

Occurances

Geological Setting:

In hydrothermal deposits formed at relatively high temperature, in pyrrhotite–pentlandite ores in which it commonly occurs as intimate oriented intergrowths with chalcopyrite. Cubanite may exsolve from chalcopyrite below about 200° C – 210° C. A rare constituent of some carbonaceous chondrite meteorites.

Common Associations:

Chalcopyrite, Gold, Pentlandite, Pyrite, Pyrrhotite, Sphalerite

Type Locality:

Barracanao, Cuba

Year Discovered:

1843

View mineral photos:

Cubanite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Cubanite (also known as "Chalmersite") is a rare copper mineral and a very rare gem. It is opaque with a bright metallic luster and very striking brassy to bronzey color. It is a minor ore of copper and often associated with other copper ores such as Chalcopyrite and also associated with Gold in some Gold mines.

Notable occurrences of Cubanite include Barracanao, Cuba; Morro Velho gold mine, Minas Gerais, Brazil; Harz Mountains, Germany and the Henderson Mine, Chibougamau, Quebec, Canada.
 

  
Cubanite gems for sale: