Location: |
Sulphides associated with serpentinized dunite. Unst, Shetland Islands, Britain |
Major Minerals: |
Magnetite, heazlewoodite, pentlandite |
Minor Minerals: |
Chromite, ferritchromit, nickel arsenides, breithauptite |
Trace Minerals: |
Include millerite, godlevskite, chalcocite, bornite, native copper, native silver, Pd-Cu antimonides, irarsite, geversite, sperrylite, Pt-Fe alloys, molybdenite |
Textures: |
Characteristic intergrowths include magnetite-pentlandite and heazlewoodite ± nickel arsenide minerals and breithauptite. Magnetite forms rims around and lies along the cleavage planes of pentlandite. Pentlandite alters along grain boundaries to heazlewoodite which carries crystallographically oriented NiAs blebs and alters to millerite. Crystallographically oriented bornite-chalcocite intergrowths occur in relict olivine and in ferritchromit rims around chromite. Nickel-bearing sulphides are replaced by copper sulphides and native copper within silicates. The Pd-Cu antimonides are zoned and are associated with breithauptite |
References: |
Pritchard and Neary, 1981; Pritchard et al., 1986; 1987 |