Paraotwayite

paraotwayite

otwayite

millerite

polydymite

Images

Formula: Ni(OH)2-x(SO4,CO3)0.5x
Sulphate, nickel-bearing mineral
Crystal system: Monoclinic
Specific gravity: 3.30 measured, 3.52 calculated
Hardness: 4
Streak: White
Colour: Emerald-green
Luminescence: No fluorescence under long wave or short wave UV
Solubility: Not attacked by cold hydrochloric or nitric acid
Environments

Metamorphic environments
Hydrothermal environments

Localities

At the type locality, the Otway Ni deposit, Nullagine, East Pilbara Shire, Western Australia, the nickel minerals occur in shears in serpentinised peridotite, and consist mainly of nodular millerite, polydymite and pecoraite in a matrix of nickel carbonates and silicates. The nickel mineralisation is attributed to hydrothermal and metasomatic activity along the shears, and the primary assemblage has been subjected to some supergene alteration due to the effects of weathering.
Paraotwayite has been found in two specimens. Both specimens consist largely of millerite nodules partly altered to polydymite, in a matrix of green nickel-bearing chrysotile. Cutting across this assemblage are veinlets of dolomite, gaspéite and, to a lesser extent, paraotwayite.
Paraotwayite occurs as masses of parallel to sub-parallel fibres up to about 0.5 mm long and 5 microns wide. It is emerald-green in hand specimen, with a silky lustre, and is virtually indistinguishable from otwayite, which has a similar occurrence (CM 25.3.409-411).
Paraotwayite from the Otway Ni deposit - Image

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