Characterization of Extractable Uranium in Domiasiat Sandstones, West Khasi Hills District, Meghalaya

Uranium mineralisation in Domiasiat sandstone is due to migration and fixation by biogenic processes, and leaching and redistribution by surface and groundwater. Fine-sized pitchblende and coffinite are associated with carbonaceous matter and pyrite. Characterization of the extractable uranium indicates that its nature varies from sample to sample and appears to be dependent on pH, Eh and the amount of soluble sulphates in them and to some extent on gangue minerals like calcite which can neutralise the acid component. It is inferred that alteration of sulphides and formation of sulphates results in an acidic condition favouring mobilisation.