An abrasive is a material / mineral used to smooth, polish, cut, grind, another substance This is a common mineral used widely in technological & industrial applications. Natural abrasives consist of pumice, corundum , sand and ground quartz. Alumina (aluminum oxide) and Carborundum (silicon carbide) are synthetically formed abrasives. The hardest abrasives are synthetic or natural diamonds used in the form of dust or minuscule stones.