Silicon carbide (SiC), also known as carborundum, is a compound of silicon and carbon with the chemical formula SiC. It occurs in nature as the extremely rare mineral moissanite. Silicon carbide powder has been mass-produced since 1893 for use as an abrasive. Grains of silicon carbide can be bonded together by sintering to form tough ceramics widely used in applications requiring high endurance, such as car brakes, car clutches and ceramic plates in bulletproof vests.