Brittle green mass of pimelite, nimite and chrysoprase. From Mindat: 'Excavation of the locality arranged by the 1st Mindat conference organizers in July, 2010 resulted in a major find of exceptional pimelite specimens and a mineralogical investigation is underway to re-validate the species.' — Photo: David Hospital · CC BY-SA 4.0
Nimite
A nickel-bearing member of the chlorite group — a green phyllosilicate of nickel deposits.
Intro adapted from Wikipedia (CC BY-SA).
Nimite is an IMA-recognized mineral species in the silicate class, with the chemical formula (Ni,Mg,Al)₆(Si,Al)₄O₁₀(OH)₈.
It crystallizes in the monoclinic crystal system (space group C2/m). It is a member of the Chlorite, Clay structural group.
Key properties: Mohs hardness 3; specific gravity 3.123; optically biaxial.
IMA symbol Nim, IMA status: approved, named in 1968.
Found in a small tabular body of nickeliferous serpentinite, probably a contact deposit, along the junction of quartzite and an ultramafic intrusive; it appears to have formed at ~730° C and < 2 kbar during thermal metamorphism.
It is found associated with Willemseite, nickeloan talc, ferroan trevorite, bonaccordite, violarite, millerite, reevesite, goethite.
An acronym for the National Institute of Metallurgy of South Africa.