An abrasive substance is a material that is used to grind, polish, or clean surfaces. Two common abrasive substances are EMERY and CARBORUNDUM. EMERY is a naturally occurring mineral composed of corundum, magnetite, and other minerals. It is often used in sandpaper and other abrasive products. CARBORUNDUM is a man-made material made from silicon carbide. It is used in grinding wheels, abrasive cloths, and other abrasive products.