English: Carborundum (silicon carbide) is produced artifically in large quantities as an abrasive. Most is crushed and used in griding grits and abrasive papers. This specimen shows coarsely crystallised hexagonal plates of silicon carbide, with typical rainbow irridescent surface colours.

It does occur in naturally as well, as the mineral moissanite, but it is very rare, and crystals are almost always tiny or microscopic.