mineral

Almandine Garnet

Iron aluminum silicate (Fe3Al2(SiO4)3)

Hardness: 7-7.5 (Mohs scale); Color: Deep red to reddish-brown/purple; Luster: Vitreous to resinous; Crystal structure: Isometric (dodecahedral); Cleavage: Indistinct; Specific gravity: 3.93 - 4.30

Hardness: 7-7
Color: Deep red to reddish-brown/purple
Luster: Vitreous to resinous

Identified March 15, 2026More mineral →

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Physical properties

Hardness: 7-7.5 (Mohs scale); Color: Deep red to reddish-brown/purple; Luster: Vitreous to resinous; Crystal structure: Isometric (dodecahedral); Cleavage: Indistinct; Specific gravity: 3.93 - 4.30

Formation & geological history

Formed primarily in metamorphic rocks like mica schists and gneisses through the regional metamorphism of clay-rich sediments. It can also occur in some igneous rocks like granites.

Uses & applications

Predominantly used as a gemstone in jewelry (cabochons and faceted stones) and as an industrial abrasive for sandblasting and water-jet cutting due to its hardness.

Geological facts

Almandine is the most common garnet and is the traditional birthstone for January. It was historically called 'Carbuncle' in ancient times. Some rare specimens exhibit asterism (the star effect).

Field identification & locations

Identify in the field by its distinct crystal shape (12-sided dodecahedrons), its lack of cleavage, and its high hardness relative to surrounding rock. Common in metamorphic belts worldwide like those in New York, Idaho, and India.

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

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Epidote

Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

mineral