Nullaginite

nullaginite

pecoraite

gaspeite

serpentine

Images

Formula: Ni2(CO3)(OH)2
Anhydrous carbonate containing hydroxyl, rosasite group
Crystal System: Monoclinic
Specific gravity: 3.56 measured, 4.10 calculated
Hardness: 1½ to 2
Colour: Green
Luminescence: Not fluorescent in UV
Environments

Metamorphic environments

Localities

At the type locality, the Otway Ni deposit, Nullagine, East Pilbara Shire, Western Australia, nullaginite occurs as nodules and as veinlets. The nodules, ovoid to irregular in shape, bright green in colour and up to 2 mm across, are found in a matrix of chlorite and nickel-bearing serpentine. The nodules commonly contain magnetite, which is usually distributed around the grain margins. The nodular nullaginite is commonly intergrown with pecoraite, which forms nodules virtually identical in appearance to those of nullaginite. In a few samples the nullaginite has been altered to a pale green, chalky material that gives X-ray-diffraction patterns corresponding to nullaginite and gaspéite. These chalky nodules seem to be a product of decomposition of the nullaginite.
The nullaginite occurring in veinlets consists of tiny cross-fibre crystallites and is virtually identical in appearance to otwayite. The nullaginite is generally intergrown with pecoraite, and it seems that the core of the veinlets is probably magnesium-bearing pecoraite (CM 19.315-324).

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