Nickel-bearing djerfisherite in gehlenite-spurrite skarn at Kushiro, Hiroshima Prefecture, Japan

Djerfisherite occurs intimately intergrown with troilite and pentlandite in gehlenite-spurrite skarn at Kushiro, mainly as inclusions in gehlenite and andradite grains. The mode of occurrence indicates that the djerfisherite formed in the culminated stage of the contact metamorphic-metasomatic proce ss. The chemical compositions of the mineral are approximately represented by a formula of K6Na(Fe,Ni,Cu)(24)S26Cl with Ni up to 4.85. It is likely th at high temperature condition corresponding to the formation of gehlenite-s purrite skarn as well as low f(O2) and f(S2) conditions are responsible for the formation of djerfisherite in the potassium-rich chemical environments .