Gaspeite
| Gaspéite | |
|---|---|
Gaspéite
|
|
| General | |
| Category | Carbonate mineral, anhydrous subgroup |
|
Formula (repeating unit) |
(Ni,Fe,Mg)CO3 |
| Strunz classification | 5.AB.05 |
| Dana classification | 14.01.01.08 Calcite group |
| Crystal system | Trigonal |
| Crystal class | Hexagonal scalenohedral (3m) H-M symbol: (3 2/m) |
| Space group | R3c |
| Identification | |
| Color | Pale green, light grass or apple green |
| Crystal habit | Rhombic crystal aggregates, nodular concretions (botryoidal), massive |
| Cleavage | {1011} Good |
| Fracture | Uneven |
| Mohs scale hardness | 4.5 - 5 |
| Luster | Vitreous to dull |
| Streak | Yellow green |
| Diaphaneity | Translucnt |
| Specific gravity | 3.71 |
| Optical properties | Uniaxial (-) |
| Refractive index | nω = 1.830 nε = 1.610 |
| Birefringence | δ = 0.220 |
| Solubility | HCl soluble |
| Other characteristics | Weakly magnetic |
| References | |
Gaspéite, a very rare nickel carbonate mineral, with the formula (Ni,Fe,Mg)CO3, is named for the place it was first described, in the Gaspé Peninsula, Québec, Canada.
Gaspéite is the nickel rich member of the calcite group. A solid solution series exists between all members of this group with divalent cations readily exchanged within the common crystal structure. It forms massive to reniform pappillary aggregates in fractures, bottryoidal concretions in laterite or fracture infill. It is also present as stains and patinas on iron oxide boxworks of gossanous material.
Gaspéite is formed in the regolith as a supergene enrichment mineral of hypogene nickel sulfide minerals, generally in arid or semi-arid environments which produce conditions amenable to concentration of calcareous or carbonate minerals in the weathering profile.
Gaspéite from Widgiemooltha is associated with talc carbonated komatiite-associated nickel sulfide gossans and is probably formed by substitution of nickel into carbonates such as magnesite which are formed by oxidation of the talc-carbonate lithology, and of primary and supergene nickel sulfide minerals.
Gaspéite is formed from a similar process to the weathering of other sulfide minerals to form carbonate minerals. The sulfide minerals which are weathered to produce gaspéite are pentlandite, violarite, millerite and rarely nickeline.
Gaspéite is known from a handful of locations worldwide. Aside from its type locality in Canada, gaspéite is found in the nickeliferous gossans of Kambalda type komatiitic nickel ore deposits in Kambalda, and nearby Widgie Townsite, Widgiemooltha, both south of Kalgoorlie, Western Australia, in both locations also associated with garnierite and kambaldaite.
...
Wikipedia