Metasomatite-albitite-hosted uranium mineralisation in Rajasthan

In 1994, AMD initiated ground radiometric reconnaissance surveys to locate metasomatite/albitite- hosted uranium mineralisation in Rajasthan. Exploration is focussed on the eastern fringe of Khetri sub-basin in the North Delhi Fold Belt and further south in the South Delhi Fold Belt along the contact of older basement rocks and Delhi Supergroup. Uranium mineralisation associated with sodic/potassic metasomatites occurs at various locations in the 320-km long Albitite-Microclinite-Pyroxenite zone, extending from Dancholi in NE to Tal in SW. Uranium mineralisation occurs primarily within zones of cataclasism, hosted by albitised carbonaceous quartz-chlorite/biotite schist, albitised pyroxenite and tremolite-rich rock, chloritised syenite and hetrolithic breccia. Chloritisation and carbonatisation are the prominent wall-rock alterations associated with this uranium mineralisation. Detailed drilling at one anomaly (Rohil) delineated two medium-size uranium ore bodies having strike continuity of 500m and 300m over a mineralised strike length of 1850m. Preliminary exercise on ore reserve estimation indicated 1000 te of eU3O8 at an average grade of 0.081% up to a depth of 200m. The ore is amenable to acid leaching with more than 90% recovery. Other anomalies that have not yet been thoroughly evaluated may represent additional significant uranium reserves. (author)