Petrographic studies of Proterozoic pyriteferous granitoids forming basement for upper cretaceous Mahadek sediments from Wahkyn area reveal interesting textural peculiarities of Pyrite. These pyrites also reveal interesting structural peculiarities. The three textural pyrite varieties found in the granitoids are: framboidal, colloform and recrystallised which appear both as composite aggregate as well as independent units. Various textures and variation in reflectivity, microhardness and elemental distribution of the pyrites are described. Average Co/Ni ratio along with the textural manifestation of these pyrites attests their sedimentary origin.In Wahkyn area, the core samples from several vertical boreholes (drilled up to a maximum depth of 93.40 m) were studied. Thickness of Mahadek sediments including basal conglomerate in the boreholes vary from 47.95 to 88.20 m and basement granitoids vary from 0.85 m to 5.40 m. The studied samples represent depths of 53.30 to 93.40 m and were drawn from depths of 0.5 m to 1.0 m below the sediment -basement contact.This paper describes the petrography, ore petrography and chemistry of pyrites occurring in the basement granitoids of Wahkyn area of West Khasi hills, Meghalaya.

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