Cuprospinel

Cuprospinel
General
Category	Oxide mineral Spinel group
Formula (repeating unit)	CuFe2O4 or (Cu,Mg)Fe2O4
Strunz classification	4.BB.05
Crystal system	Isometric
Crystal class	Hexoctahedral (m3m) H-M symbol: (4/m 3 2/m)
Space group	Cubic Space group: Fd3m
Identification
Formula mass	239.23 g/mol
Color	Black, gray in reflected light
Crystal habit	Irregular grains, laminae intergrown with hematite
Mohs scale hardness	6.5
Luster	Metallic
Streak	Black
Diaphaneity	Opaque
Specific gravity	5 - 5.2
Optical properties	Isotropic
Refractive index	n = 1.8
References

Cuprospinel, occurs naturally in Baie Verte, Newfoundland, Canada. The mineral was found in an exposed ore dump, on the property of Consolidated Rambler Mines Limited near Baie Verte, Newfoundland. The mineral was first characterized by Ernest Henry Nickel, a mineralogist with the Department of Energy, Mines and Resources in Australia, in 1973.

Cuprospinel, is an inverse spinel with the formula CuFe₂O₄, where copper substitutes some of the iron cations in the structure. Its structure is similar to that of magnetite, Fe₃O₄, yet with slightly different chemical and physical properties due to the presence of copper.

Cuprospinel, like many other spinels has the general formula AB₂O₄. Yet, cuprospinel is an inverse spinel in that its A element, in this case copper (Cu²⁺), only occupies octahedral sites in the structure and the B element, iron (Fe²⁺ and Fe³⁺), is split between the octahedral and tetrahedral sites in the structure. The Fe²⁺ species will occupy some of the octahedral sites and there will only be Fe³⁺ at the tetrahedral sites. Cuprospinel adopts both cubic and tetragonal phases at room temperature, yet as temperature is elevated the cubic form is most stable.

Cuprospinel is used in various industrial processes as a catalyst. An example is the water–gas shift reaction:

This reaction is particularly important for hydrogen production and enrichment.

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