mineral

Carborundum (Silicon Carbide)

Silicon Carbide (SiC)

Hardness: 9-9.5 (Mohs scale), Color: iridescent black, green, or blue, Luster: metallic or submetallic, Crystal structure: hexagonal/rhombohedral, Specific gravity: 3.21

Hardness: 9-9

Identified June 5, 2026More mineral →

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Physical properties

Hardness: 9-9.5 (Mohs scale), Color: iridescent black, green, or blue, Luster: metallic or submetallic, Crystal structure: hexagonal/rhombohedral, Specific gravity: 3.21

Formation & geological history

While naturally occurring as the rare mineral Moissanite in meteorites, nearly all terrestrial specimens are synthetic, produced by heating silica sand and carbon in an electric resistance furnace at extreme temperatures (Acheson process).

Uses & applications

Used extensively as an abrasive for cutting and grinding, as a semiconductor in electronics, and as a decorative/collectible specimen due to its iridescence.

Geological facts

Carborundum is almost as hard as diamond and was discovered by Edward Goodrich Acheson in 1891 while he was attempting to create synthetic diamonds. Its rainbow sheen is caused by a thin layer of silicon dioxide that forms on the surface.

Field identification & locations

Identify by its characteristic iridescent 'oil-slick' colors, extremely sharp/brittle edges, and its ability to scratch almost any other material besides diamond. It is not found naturally in large chunks on Earth.