- Otwayite
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Otwayite General Category Carbonate mineral Chemical formula Ni2CO3(OH)2 Strunz classification 5.DA.15 Unit cell a = 10.18 Å, b = 27.4 Å, c = 3.22 Å; Z = 8 Identification Color Bright green Crystal habit Sprays of Fibrous bundles oriented perpendicular to veinlet walls; spherules and claylike coatings Crystal system Orthorhombic Mohs scale hardness 4 Luster Silky to waxy Diaphaneity Opaque to translucent Specific gravity 3.41 Optical properties Biaxial Refractive index nα = 1.650 nγ = 1.720 Birefringence δ = 0.070 Pleochroism Weak Dispersion Very strong References [1][2] Otwayite, Ni2CO3(OH)2, is a hydrated nickel carbonate mineral. Otwayite is green, with a hardness of 4, a specific gravity of 3.4, and crystallises in the orthorhombic system.
Occurrence
Otwayite is found in association with nullaginite and hellyerite in the Otway nickel deposit. It is found in association with theoprastite, hellyerite, gaspeite and a suite of other nickel carbonate minerals in the Lord Brassey Mine, Tasmania. Otwayite is found in association with gaspeite, hellyerite and kambaldaite in the Widgie Townsite nickel gossan, Widgiemooltha, Western Australia. It is also reported from the Pafuri nickel deposit, South Africa. It was first described in 1977 from the Otway Nickel Deposit, Nullagine, Pilbara Craton, Western Australia and named for Australian prospector Charles Albert Otway (1922– ).[2]
References
- Nickel, E. H.; Robinson, B. W.; Davis, C. E. S.; MacDonald, R. D. (1977). "Otwayite, a new nickel mineral from Western Australia". American Mineralogist 62: 999–1002. http://rruff.info/rruff_1.0/uploads/AM62_999.pdf.
- Nickel, E. H.; Hallbert, J. A.; Halligan, R. (1979). "Unusual nickel mineralization at Nullagine, Western Australia". Journal of the Geological Society of Australia 26: 61–71.
- Henry, D. A. & Birch, W. D. (1992): Otwayite and theophrastite from the Lord Brassey Mine, Tasmania. Mineral. Mag. 56, 252-255.
- Andersen, P., Bottrill, R. & Davidson, P. (2002): Famous mineral localities: The Lord Brassey mine, Tasmania. Mineral. Rec. 33, 321-332.
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