Hellyerite

Hellyerite, NiCO3·6H2O, is an hydrated nickel carbonate mineral. It is light blue to bright green in colour, has a hardness of 2.5, a vitreous luster, a white streak and crystallises in the monoclinic system. The crystal habit is as platy and mammillary encrustations on its matrix. The environment of formation, associated only with metamorphosed ultramafic rocks, is diagnostic compared with gaspeite, another nickel carbonate which is associated with supergene weathering of nickel sulfides.
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General Information:
 Chemical Formula:
NiCO3·6(H2O)
 Composition:
(Molecular Weight = 226.79 gm)
Nickel 25.88 % Ni
Hydrogen 5.33 % H 
Carbon 5.30 % C 
Oxygen 63.49 % O 
 Empirical Formula:
Ni(CO3)·6(H2O)
 IMA Status:
Approved IMA 1959
Physical Properties:
 Color:
light blue.
 Density:
1.97
 Hardness:
2.5 - Finger Nail
 Luster:
Vitreous (Glassy)
 Streak:
white
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