Summary:
Disseminated textured magmatic nickel-sulphide mineralisation associated with a metamorphosed ultramafic intrusion.
The stratigraphy in the Mt Keith region is composed of ultramafic sequences (olivine cumulates and thin spinifex textured flows), basalts, volcanic and volcanoclastic rocks and sedimentary rocks The ultramafic sequence at Mt Keith is lenticular It faces W, dips 80- 85, and has undergone low- to mid-greenschist metamorphism The major komatiitic rock types include sulphide-bearing olivine mesocumulate, olivine orthocumulate, talc-carbonate altered orthocumulates and a porphyry olivine rock The non sulphide mineralogy consists of hydrated Mg silicates (Iizardite, antigorite, chrysotile, talc), Mg oxy carboxyl hydroxides (brucite, stichtite, pyroaurite, iowaite), spinels (chromite, magnetite), carbonates (magnesite, dolomite), tremolite-actinolite and chlorite The disseminated sulphide mineralogy is dominated by pentlandite, with minor millerite, viola rite and pyrrhotite Trace amounts of pyrite, chalcopyrite, heazlewoodite, gersdorffite, polydymite, tochilinite, sphalerite and exsolved Co sulphides are also present.