What is Rammelsbergite?
Rammelsbergite is a dense nickel arsenide with metallic grey colour, an important member of nickel-arsenic ore assemblages and a specialist collector mineral.
Mineralogy and crystal structure
Reference formula: NiAs2. Rammelsbergite is orthorhombic and forms a dimorph relationship with pararammelsbergite. Its metallic appearance is not enough for identification, and its arsenic content requires responsible display. Rammelsbergite is classified with arsenides and has a orthorhombic crystal system. Typical hardness is 5.5–6 on the Mohs scale and specific gravity is approximately 7.0–7.6.
Colour, lustre and habit
Typical colours include tin-white, silver-grey, grey, black. The usual prismatic, acicular, massive habit and metallic, sub-metallic lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Rammelsbergite forms in or is associated with hydrothermal nickel-cobalt-arsenic veins, metamorphic ore deposits and alteration zones. Important documented localities include Germany, Morocco, Canada, Norway, Sweden, the Czech Republic and other nickel-arsenic districts.
A dense nickel arsenide with ore-deposit context
Rammelsbergite appeals to collectors of classic ore minerals because a small metallic specimen records nickel, cobalt and arsenic transport in a hydrothermal vein. The best examples are sold with locality and analytical context.
Collecting and care
Keep sealed and dry, avoid dust and do not cut or grind. Wash hands after handling and keep away from food, children and pets.
