mineral

Garnet

Almandine Garnet (Fe3Al2(SiO4)3)

Hardness: 6.5–7.5 Mohs scale. Color: Deep reddish-brown to dark purple/black. Luster: Vitreous to resinous. Crystal structure: Isometric (dodecahedral). Cleavage: None. Specific gravity: 3.5–4.3.

Hardness: 6
Color: Deep reddish-brown to dark purple/black
Luster: Vitreous to resinous

Identified June 23, 2026More mineral →

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Physical properties

Hardness: 6.5–7.5 Mohs scale. Color: Deep reddish-brown to dark purple/black. Luster: Vitreous to resinous. Crystal structure: Isometric (dodecahedral). Cleavage: None. Specific gravity: 3.5–4.3.

Formation & geological history

Formed under high-pressure, high-temperature metamorphic conditions, typically in mica schists or gneisses. Found in regions of plate tectonic convergence.

Uses & applications

Abrasives (sandblasting, waterjet cutting), gemstones for jewelry to celebrate January birthdays, and as an index mineral for determining metamorphic grade.

Geological facts

Garnets have been used as gemstones since the Bronze Age. They are the official birthstone for January and are famous for being found as perfectly formed twelve-sided crystals (dodecahedrons).

Field identification & locations

Identify by its distinctive crystal habit (soccer ball-like shape), lack of cleavage, and high hardness. Commonly found in metamorphic terrains like the Adirondack Mountains or the Alps.