mineral

Almandine Garnet (Tumbled)

Fe3Al2(SiO4)3

Hardness: 6.5-7.5 on Mohs scale. Color: Deep dark red, brownish-red to nearly black with internal fractural reflections. Luster: Vitreous to resinous. Structure: Isometric/cubic. Cleavage: None (indistinct, conchoidal fracture). Specific gravity: 4.1-4.3.

Hardness: 6
Luster: Vitreous to resinous

Identified July 27, 2026More mineral →

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Physical properties

Formation & geological history

Formed under high-pressure regional metamorphism of argillaceous (clay-rich) rocks like mica schists, gneisses, and amphibolites. Also occurs in some igneous rocks.

Uses & applications

Used widely as a gemstone in tumbled or faceted jewelry, as an industrial abrasive (waterjet cutting, sandblasting), and as popular polished pocket stones for mineral collectors.

Geological facts

Almandine is the most common garnet species. Its deep reddish-brown tone is caused by the presence of iron (Fe2+). Historically, dark red garnets were known as carbuncles.

Field identification & locations

Identified by its high density/weight for its size, glassy vitreous luster, dark red to black hue, and high hardness. Commonly found in India, Madagascar, Brazil, Sri Lanka, and the United States (Idaho, New York).