Otwayite

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Otwayite
General
Category Carbonate mineral
Formula
(repeating unit)
Ni2CO3(OH)2
Strunz classification 05.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[edit]

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 (born 1922).[2]

References[edit]

  • 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. 
  • 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. doi:10.1080/00167617908729067. 
  • 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.