Carborundum or silicon carbide, of formula SiC, is a synthetic industrial abrasive
made from silicon (and therefore quartz
). It crystallizes in ovens in the form of aggregates of sharp black lamellae with a strong metallic luster, rich in multicolored iridescence. These aggregates are then ground to obtain the black powder marketed as an abrasive.
Many particularly aesthetic specimens of carborundum are, however, torn from grinders, and are found in traders and in mineralogical exchanges under various names, mixing originality, poetry, ignorance and even fraud.