Rajasthan is rich in non-metallic and industrial minerals. The minerals found in the state include Limestone, Dolomite, Lignite, Barytes, Calcite, Clay, Emerald, Feldspar, Emerald, Fluorite, Garnet, Gypsum, Potash, Rock-Phosphate, Silica sand, Siliceous Earth, Soapstone, Wollastonite, Marble, Granite, Sand stone and Slates. The process of the mineral grinding industry involves generation of harmful air pollutants and requires water in the process and hence it has been categorized as red category industry.