Stannite

Stannite is a mineral, a sulfide of copper, iron, and tin, in the category of thiostannates.

Stannite
General
Category	Sulfide mineral
Formula	Cu2FeSnS4
IMA symbol	Stn[1]
Strunz classification	2.CB.15a
Crystal system	Tetragonal
Crystal class	Scalenohedral (42m) H-M symbol: (4 2m)
Space group	I42m
Unit cell	a = 5.4432, c = 10.7299 [Å]; Z = 2
Identification
Color	Steel-gray to iron-black, may tarnish blue
Crystal habit	Rarely as pseudo-octahedral crystals also massive, granular, and disseminated
Twinning	Penetration twins on {102}
Cleavage	Indistinct on {110} and {001}
Fracture	Uneven
Mohs scale hardness	4
Luster	Metallic
Streak	Black
Diaphaneity	Opaque
Specific gravity	4.3 – 4.5
References	[2][3][4]

Background

The chemical formula is Cu₂FeSnS₄. Zinc commonly occurs with the iron and trace germanium may be present.^[4] Stannite is used as an ore of tin, consisting of approximately 28% tin, 13% iron, 30% copper, 30% sulfur by mass. It is found in tin-bearing, hydrothermal vein deposits occurring with chalcopyrite, sphalerite, tetrahedrite, arsenopyrite, pyrite, cassiterite, and wolframite.^[2]

It is also known as bell metal ore as tin is an important constituent of bell metal. It is thought the exploitation of tin deposits in Cornwall led to an expansion in bell founding.

The name comes from the Latin for tin: stannum. It was first described in 1797 for an occurrence in Wheal Rock, St. Agnes, Cornwall, England.^[4]

See also

• Kesterite