mineral

Almandine Garnet

Almandine (Fe3Al2(SiO4)3)

Hardness: 6.5-7.5 on the Mohs scale. Color: Deep red, brownish-red, or reddish-black. Luster: Vitreous to resinous. Crystal structure: Isometric (dodecahedral or trapezohedral). Cleavage: None (conchoidal fracture). Specific Gravity: 3.5-4.3.

Hardness: 6
Color: Deep red, brownish-red, or reddish-black
Luster: Vitreous to resinous

Identified January 23, 2026More mineral →

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Physical properties

Formation & geological history

Primary formation occurs in metamorphic rocks such as mica schists and gneisses through the regional metamorphism of clay-rich sedimentary rocks. It can also form in igneous rocks like pegmatites or granites. Common throughout geological history from the Precambrian to Cenozoic eras.

Uses & applications

Predominantly used as a gemstone in jewelry (birthstone for January). Industrially, it is used as an abrasive in sandblasting, waterjet cutting, and sandpaper due to its hardness and lack of cleavage.

Geological facts

Almandine is the most common member of the garnet group. It was historically known as 'carbuncle' in ancient times. Large deposits in New York led to it being named the state gemstone. It is often found as 'star garnets' in Idaho, which exhibit asterism.

Field identification & locations

Identify in the field by its distinct 12-sided crystal shape (dodecahedron), deep red color, and high density. It won't react with acid and is hard enough to scratch glass. Commonly found in metamorphic terrains like the Alps, Himalayas, and the Adirondack Mountains.