Podiform chromite, Unst, Shetland Islands. Britain

Major Minerals:


Minor Minerals:

Ferritchromit, magnetite, pentlandite, heazlewoodite, millerite

Trace Minerals:

Include sperrylite, laurite, stibiopalladinite, irarsite-hollingworthite, native gold, native copper, copper-gold alloys, bornite, chalcocite, valleriite, godlevskite, nickel arsenides, gold tellurides


Ferritchromit rims are extensively developed about shattered chromite grains. Nickel-iron and nickel sulphides and arsenides are associated with alteration and serpentinization of the primary olivine. Alteration of pentlandite to heazlewoodite and to millerite with a trellis-like texture is common. Rare, euhedral platinum group minerals occur within chromite grains, but most platinum group minerals are associated with hydrothermal alteration processes and occur as inclusions within ferritchromit rims or within the secondary silicates


Pritchard and Neary, 1981; Pritchard et al., 1986; 1987