Mineral

Almandine Garnet

Almandite (Fe3Al2(SiO4)3)

Hardness: 6.5-7.5 on the Mohs scale. Color: Deep red, reddish-brown, or blackish-red. Luster: Vitreous to resinous. Crystal Structure: Isometric (dodecahedral or trapezohedral). Cleavage: None (conchoidal fracture). Specific Gravity: 4.1-4.3.

Hardness: 6
Color: Deep red, reddish-brown, or blackish-red
Luster: Vitreous to resinous

Identified March 16, 2026More mineral →

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Physical properties

Formation & geological history

Formed through regional metamorphism of clay-rich sedimentary rocks (shales) into schists and gneisses, or occasionally found in igneous rocks like granites and pegmatites. These specimens can range from hundreds of millions to billions of years old.

Uses & applications

Primary use as an industrial abrasive (sandpaper, waterjet cutting), semi-precious gemstone in jewelry, and as a 'geothermometer' to help scientists understand the pressure and temperature history of the earth's crust.

Geological facts

Garnet is the birthstone for January. Almandine is the most common member of the garnet group. When garnet crystals are particularly well-formed and dark, they were historically called 'carbuncles.'

Field identification & locations

Identify in the field by its distinct 12-sided (dodecahedral) shape, high density, and lack of cleavage. Often found in mica schists where the shiny mica flakes surround the harder garnet 'balls.' Common locations include New York (USA), India, Brazil, and Madagascar.