Gudmundite from Base Metal Sulphide Deposit of Askot, Pithoragarh District, (U. P.)

Gudmundite occurs as a common mineral constituent in the polymetallic ores of Askot. Three distinct modes of formation of gudmundite have been observed: (a) as a product of decomposition of tetrahedrite, (b) as a substitution product in cubanite and (c) as a reaction rim around breithauptite. The breakdown of tetrahedrite to chalcopyrite-gudmundite intergrowth signifies the retrograde metamorphism of this high temperature ore body. The eutectoid intergrowth between cubanite and gudmundite has resulted from a late stage hypogene replacement by addition of antimony.