Trevorite

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Trevorite
General
Category Oxide minerals
Spinel group
Spinel structural group
Formula
(repeating unit)
NiFe3+2O4
Strunz classification 04.BB.05
Dana classification 7.2.2.5
Crystal symmetry Isometric hexoctahedral
H-M symbol: (4/m32/m)
Space group: F d3m
Unit cell a = 8.41 Å; Z=8
Identification
Color Black, greenish hue
Crystal habit Granular to massive, rare as minute octahedra
Crystal system Cubic
Cleavage None
Fracture Uneven
Tenacity Brittle
Mohs scale hardness 5
Luster Metallic to sub-metallic
Streak Brown
Diaphaneity Opaque, transparent in thinnest fragments
Specific gravity 5.164
Refractive index n = 2.41 (calculated)
Other characteristics Highly magnetic
References [1][2][3]

Trevorite is a rare nickel iron oxide mineral belonging to the spinel group. It has the chemical formula NiFe3+2O4. It is a black mineral with the typical spinel properties of crystallising in the cubic system, black streaked, infusible and insoluble in most acids.

There is at least partial solid solution between trevorite and magnetite, with many magnetites from ultramafic rocks containing at least trace amounts of Ni. Fe2+ and Mg2+ may substitute for Ni in trevorite.

Discovery and occurrence[edit]

It was first described for an occurrence in the Bon Accord Nickel Deposit, Bon Accord, Barberton, Mpumalanga, South Africa, in 1921 and was named for Major Tudor Gruffydd Trevor (1865–1958) who was a mining inspector in South Africa.[3][1]

In the Bon Accord deposit it occurred as a contact deposit between an ultramafic intrusion and a quartzite. In an occurrence at Mt. Clifford, Australia, it occurs associated with a nickel sulfide orebody adjacent to a gabbro which intruded peridotite. Associated minerals include nimite, willemseite, nickeloan talc, violarite, millerite, reevesite and goethite at Bon Accord; and with native nickel, heazlewoodite and millerite at Mt. Clifford.[1]

It has also been reported from the Logatchev-1 hydrothermal field on the Mid-Atlantic Ridge; in the Hatrurim Formation in the Negev Desert in Israel; the Josephine Creek District, Josephine County, Oregon and the Gabbs District of Nye County, Nevada.[3]

References[edit]

  • Deer, W. A.; R. A. Howie; J. Zussman (1992). An Introduction to the Rock-forming Minerals. Harlow, Essex: Longman. pp. 559–563. ISBN 0-470-21809-6.