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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
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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