On the basis of source of raw materials used, industries are classified into— (i) Agro–based industries (ii) Mineral–based industries (i) Agro–based industries are based on agricultural raw materials, for example,cotton, juite, silk, woollen, sugar and edible oil. (ii) Mineral–based industries use minerals and metals as raw materials, for example iron and steel, cement, aluminium, machine tools, petrochemicals.