A Rare Calcium Rich Uraninite from Anjangira Area, Sonbhadra District, Uttar Pradesh

A variety of high calcic uraninite showing 3.26- 10.69 % of CaO has been identified in 'Anjangira' Uranium occurrence hosted by pegmatoid leucosome within migmatites forming part of Chhotanagpur Granite Gneiss Complex (CGGC), in Sonbhadra district, U.P. It is one of the two distinct types of uraninite, which occurs as inclusions within biotite and albite besides few grains along with microcline and quartz. The less abundant high calcic type of uraninite can be easily recognized under microscope due to its habit of occurrence encircled with the pale green rim of clayey matrix. The mode of occurrence of the two types of uraninite such as euhedral, rounded, corroded and in fracture form, rules out any specific mineralogical control and a metasomatic origin seems likely. Type I uraninite has an average chemical age 751 Ma and Type II (calcic) shows a variation from 621-812 Ma.