Bauxite

Bauxite is a hydrous oxide of aluminium and is the only ore from which aluminium is extracted. When pure it is white in colour. Commonly it is yellow, brown or red or a mixture of these colours. Its hardness is variable and the specific gravity is 2.5.
Bauxite is formed by prolonged weathering of aluminium bearing rocks under tropical climatic conditions. In Tamilnadu, bauxite occurs at Shevaroy hills, Yercaud in Salem district.