Fourier transform infrared (FTIR) spectroscopic technique was used to characterise the minerals in the charnockite rock samples from Kalrayan Hills, South India. Sixty-five rock samples were collected at various locations in Kalrayan Hills. Sixteen minerals such as quartz, feldspar in different structures (orthoclase, microcline and albite), hematite, kaolinite, maghemite, magnetite, gibbsite, illite, calcite, aragonite, montmorillonite, palygorskite, biotite and organic carbon were identified and characterised. Among these quartz, microcline feldspar, orthoclase feldspar and hematite are considered as major minerals and others are minor minerals. The relative distribution of major minerals was determined by calculating extinction co - efficient.
