Pararammelsbergite Locality: Keeley-Frontier Mine (Canadian Keeley; Frontier Mine; Keeley Mine), South Lorrain Township, Timiskaming District, Cobalt-Gowganda region, Ontario, Canada Original description: A 3.9 by 2.9 cms mass of silvery interlocking subhedral crystals with some tiny orthorhombic crystals in some small cavities. JSS specimen and photo. — Photo: John Sobolewski (JSS) · CC BY 3.0
Pararammelsbergite
Pararammelsbergite is an IMA-recognized mineral species in the sulfide class, with the chemical formula NiAs₂.
It crystallizes in the orthorhombic crystal system (space group Pbca). It is a member of the Löllingite structural group.
Key properties: Mohs hardness 5; specific gravity 7.12; Metallic. Anisotropism: Strong, in russet-brown, brown, yellow, gray. R1 –R2: (400) 57.3–57.7, (420) 57.7–57.9 luster.
IMA symbol Prmb, grandfathered status — known before the IMA’s founding, named in 1940.
Found in hydrothermal veins bearing Ni–Co sulfide mineralization.
It is found associated with Nickeline, skutterudite, cobaltite, löllingite, gersdorffite, rammelsbergite.
The name refers to its chemical similarity to rammelsbergite.