abrasive, material used to grind, smooth, cut, or polish another substance. Natural abrasives include sand, pumice, corundum, and ground quartz. Carborundum (silicon carbide) and alumina (aluminum oxide) are important synthetically produced abrasives. The hardest abrasives are natural or synthetic diamonds, used in the form of dust or minuscule stones.

Sharp, hard materials used to wear away the surface of softer, less resistant materials. Abrasives are indispensable to the manufacture of the highly precise components and ultrasmooth surfaces required in the manufacture of automobiles, airplanes and space vehicles, mechanical and electrical appliances, and machine tools. Abrasives may be natural (e.g., diamond, corundum, emery) or synthetic (e.g., silicon carbide or Carborundum, synthetic diamond, alumina—a synthetic form of corundum). They range from the relatively soft particles used in household cleansers and jeweler's polish to diamonds.

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