Mineral Database (Saesneg yn unig)

Mineral Database (Saesneg yn unig)

Nickeline

Crystal System: Hexagonal
Formula: NiAs
Status of Occurrence: Confirmed Occurrence
Distribution: Rare
Chemical Composition: Nickel arsenide
Method(s) of Verification: Great Orme Copper Mines - EMPA (Parnell, 1988).
Chemical Group:
  • Sulphides
Geological Context:
  • Igneous
  • Hydrothermal : Mississippi Valley Type veins
  • Hydrothermal : epithermal polymetallic veins & pipes
Introduction: nickeline (also known as niccolite) is found most commonly in massive magmatic sulphide deposits and in silver deposits where it is associated with other Ni-Co arsenides and native silver. Neither of these associations are known from Wales. It may, however, occur as a trace mineral in other types of ore deposits.
Occurrence in Wales: nickeline is only known from a single locality in Wales. However, this is perhaps unsurprising as the classic nickeline-bearing associations do not feature in the otherwise considerable diversity of Welsh mineral deposits.
Key Localities:
  • Great Orme Copper Mines, Llandudno, Gwynedd: cobaltian nickeline with the formula (Ni0.82Co0.18)0.95As has been identified as microscopic grains occurring on fractures within uraniferous hydrocarbon from the Ty Gwyn section of these mines (Parnell, 1988).
References:
  • Parnell, J., 1988 Mineralogy of uraniferous hydrocarbons in Carboniferous-hosted mineral deposits, Great Britain.  Uranium, 4, 197-218.