Gaspeite
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Gaspeite is an extremely rare nickel carbonate mineral named for the place it was first described, in the Gaspé Peninsula, Canada.
Gaspeite's formula is (Ni,Fe,Mg)CO3 and it is a bright green mineral. 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.
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[edit] Paragenesis
Gaspeite is formed in the regolith as a supergene alteration mineral of 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.
Gaspeite 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.
Gaspeite 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 gaspeite are pentlandite, violarite, millerite and rarely nickeline.
[edit] Occurrence
Gaspeite is known from a handful of locations worldwide. Aside from its type locality in Canada, gaspeite 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.
Nickel carbonate, though not conclusively proven to be gaspeite, is also reported in hydrothermally altered ultramafic rocks in New South Wales, Australia, associated with serpentinite bodies and lode gold deposits.
Gaspeite is reported from the Lord Brassey Mine, Tasmania, in association with hellyerite.
[edit] Economic importance
Nickel carbonate minerals are too rare to be an economic source of nickel, though if they were ever found in enough quantity would make an excellent ore.
Nickel carbonate was historically worked from the goldfields of Moruya, and in Ophir, New South Wales in the late 19th century, as a source of nickel. However, such sources of nickel were only exploited because of the then scarcity of non-sulfide sources of ore and the higher cost of smelting sulfide ore.
[edit] References
- New South Wales Mining Gazette, 1897. Report of Mining Activities on the Moruya Goldfield.
- THORNBER, M. R. (1975a) Supergene alteration of sulphides, I. A chemical model based on massive nickel sulphide deposits at Kambalda, Western Australia. Chemical Geology, 15, 1-14.
- THORNBER, M. R. (1975b) Supergene alteration of sulphides, II. A chemical study of the Kambalda nickel deposits. Chemical Geology, 151 117-144.
- THORNBER, M. R., and NICKEL, E. H. (1976) Supergene alteration of sulphides, III. The composition of associated carbonates. Chemical Geology, 17, 45-72.
