Mineralogy and Origin of Jammu Bauxite

Abstract

The bauxites of Jammu comprise extensive surface spreads of generally hard dense varieties with a typical knobby appearance. The bauxite unconformably overlies Upper Pre-Cambrian limestones and underlies the Nummulitic series of Eocene age. Thickness varies from 1.5 m to 9 m. Three distinct facies are recognised: pisolitic. semi-pisolitic and non-pisolitic.

The bauxites have been analysed for their mineralogical composition adopting X-ray, D.T.A., heavy mineral analyses and optical study. The pisolitic bauxites mostly contain diaspore (A12O3 H2O) and boehmite (AI2O3. 2H2O), the semi-pisolitic bauxites contain, boehmite, limonite, and quartz. The non-pisolitic varieties contain kaolinite. Heavy mineral studies have shown the presence of magnetite, limonite, anatase and corundum. The source rocks appear to be limestones which weathered mitially into clay. The desilicification of the clays under tropical and sub-tropical climatic conditions gave rise to bauxite.