Cubanite

Cubanite is a yellow mineral of copper, iron, and sulfur, CuFe₂S₃.[3]

Cubanite
Striated, cyclically-twinned cubanite crystals from the Chibougamau mines of Quebec. (size: 1.5 x 1.3 x 1.0 cm)
General
Category	Sulfide mineral
Formula (repeating unit)	CuFe2S3
Strunz classification	2.CB.55a
Crystal system	Orthorhombic
Crystal class	Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m)
Space group	Pcmn
Unit cell	a = 6.467(1) Å, b = 11.117(1) Å, c = 6.231(2) Å; Z = 4
Identification
Color	Bronze to brass-yellow
Crystal habit	Crystals elongated to thick tabular, striated also massive
Twinning	Common with twin plane {110} in pairs, also as fourlings and pseudohexagonal sixlings
Cleavage	Parting on {110} and {130}
Fracture	Conchoidal
Mohs scale hardness	3.5-4
Luster	Metallic
Streak	Black
Diaphaneity	Opaque
Specific gravity	4.0-4.2
Optical properties	Distinctly anisotropic on polished surface
Other characteristics	Strongly magnetic
References	[1][2][3]

Iridescent and highly lustrous brass-yellow cubanite crystal from Chibougamau, Quebec (size: 1.7 x 1.0 x 0.7 cm)

Cubanite was first described in 1843 for an occurrence in the Mayarí-Baracoa Belt, Oriente Province, Cuba.[1]

Cubanite occurs in high temperature hydrothermal deposits with pyrrhotite and pentlandite as intergrowths with chalcopyrite. It results from exsolution from chalcopyrite at temperatures below 200 to 210 °C.[2] It has also been reported from carbonaceous chondrite meteorites.[2]