Rock Identifier
Almandine Garnet (Almandine (Fe3Al2(SiO4)3)) — mineral
mineral

Almandine Garnet

Almandine (Fe3Al2(SiO4)3)

Hardness: 6.5-7.5 on Mohs scale; Color: Deep red to reddish-brown; Luster: Vitreous to resinous; Crystal System: Isometric/Cubic; Cleavage: None (conchoidal fracture); Specific Gravity: 3.93-4.30.

Hardness
6
Color
Deep red to reddish-brown
Luster
Vitreous to resinous
Identified More mineral

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Physical properties

Hardness: 6.5-7.5 on Mohs scale; Color: Deep red to reddish-brown; Luster: Vitreous to resinous; Crystal System: Isometric/Cubic; Cleavage: None (conchoidal fracture); Specific Gravity: 3.93-4.30.

Formation & geological history

Forms primarily in metamorphic rocks like mica schists, gneisses, and amphibolites under high pressure and temperature conditions. It can also be found in igneous rocks like granites and pegmatites.

Uses & applications

Commonly used as a gemstone in jewelry, especially in cabochon and faceted forms. Industrially, it is used as an abrasive in sandblasting, waterjet cutting, and sandpaper due to its hardness and sharp fracture edges.

Geological facts

Garnet is the birthstone for January. Almandine is the most common member of the garnet group. The name is derived from 'Alabanda', an ancient city in Asia Minor where these stones were cut in antiquity.

Field identification & locations

Identify in the field by its deep red color, high hardness, and dodecahedral crystal habit. Often found as rounded grains in river sands or embedded in metamorphic schist. Common locations include India, Sri Lanka, Brazil, and the USA (New York, Idaho).