mineral

Carborundum (Silicon Carbide)

Silicon carbide (SiC)

Hardness: 9–9.5 on the Mohs scale; Color: Iridescent, blue, green, purple, black; Luster: Adamantine to metallic; Crystal structure: Hexagonal; Specific gravity: 3.21

Hardness: 9–9
Color: Iridescent, blue, green, purple, black
Luster: Adamantine to metallic

Identified June 30, 2026More mineral →

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Physical properties

Hardness: 9–9.5 on the Mohs scale; Color: Iridescent, blue, green, purple, black; Luster: Adamantine to metallic; Crystal structure: Hexagonal; Specific gravity: 3.21

Formation & geological history

While naturally occurring as moissanite (extremely rare and found in meteorites), large colorful iridescent chunks like this are man-made industrial by-products created via the Acheson process (fusing silica and carbon at high temperatures).

Uses & applications

Used as an abrasive (sandpaper, cutting tools), in semiconductors, as high-temperature ceramic, and as a popular decorative or educational mineral specimen.

Geological facts

Carborundum is one of the hardest known materials, nearly as hard as diamond. It was originally discovered by Edward G. Acheson while he was trying to create synthetic diamonds.

Field identification & locations

Identify by its intense rainbow iridescence (tarnish), sharp jagged edges, and extreme hardness. Though found in Minnesota, it is likely a dropped decorative piece or industrial waste rather than naturally occurring bedrock.