Rammelsbergite

Rammelsbergite is a nickel arsenide mineral with formula NiAs₂. It forms metallic silvery to tin white to reddish orthorhombic prismatic crystals, and is usually massive in form. It has a Mohs hardness of 5.5 and a specific gravity of 7.1.

Rammelsbergite
Rammelsbergite
General
Category	Mineral
Formula (repeating unit)	NiAs2
Strunz classification	2.EB.15a
Crystal system	Orthorhombic
Crystal class	Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m)
Space group	Pnnm
Unit cell	a = 4.759 Å, b = 5.797 Å c = 3.539 Å; Z = 2
Identification
Color	Tin white with a faint pinkish hue
Crystal habit	Rarely as prismatic crystals; commonly massive, granular, radial, fibrous
Twinning	On {101}
Cleavage	Distinct on {101}
Fracture	Irregular
Tenacity	Brittle
Mohs scale hardness	5.5-6
Luster	Metallic
Streak	Grayish black
Diaphaneity	Opaque
Specific gravity	7.0-7.1
Optical properties	Strongly anisotropic
Pleochroism	Weak, yellow to pinkish hue and bluish white
References	[1][2][3]

It was first described in 1854 from its type locality in the Schneeberg District in Saxony, Germany. It was named after the German chemist and mineralogist, Karl Friedrich August Rammelsberg (1813–1899).[2]

It occurs as a hydrothermal mineral in medium temperature veins association with skutterudite, safflorite, lollingite, nickeline, native bismuth, native silver, algodonite, domeykite and uraninite.[1]

References

1. Handbook of Mineralogy
2. Mindat.org
3. Webmineral data

• Mineral Galleries
• Schumann, Walter (1991). Mineralien aus aller Welt. BLV Bestimmungsbuch (2 ed.). p. 223. ISBN 978-3-405-14003-8.