Trevorite
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.
| Trevorite | |
|---|---|
Pale green nepouite appears to be far richer on this specimen, than the black with a green or brown tint trevorite. It is hard to distinguish the two. | |
| General | |
| Category | Oxide minerals Spinel group Spinel structural group |
| Formula (repeating unit) | NiFe3+2O4 |
| IMA symbol | Trv |
| Strunz classification | 4.BB.05 |
| Dana classification | 7.2.2.5 |
| Crystal system | Cubic |
| Crystal class | Hexoctahedral (m3m) H-M symbol: (4/m 3 2/m) |
| Space group | Fd3m (no. 227) |
| Unit cell | a = 8.41 Å; Z = 8 |
| Identification | |
| Color | Black, greenish hue |
| Crystal habit | Granular to massive, rare as minute octahedra |
| 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 | |
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.
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