mineral

Almandine Garnet

Iron aluminum silicate (Fe3Al2(SiO4)3)

Hardness: 6.5-7.5 on the Mohs scale. Color: Deep red to reddish-brown or black. Luster: Vitreous to resinous. Crystal structure: Isometric/Cubic (often dodecahedral). Cleavage: None. Specific gravity: 3.5-4.3.

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

Identified March 23, 2026More mineral →

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Physical properties

Formation & geological history

Formed primarily in regional metamorphic rocks such as mica schists and gneisses under high pressure and temperature. It is found in geological formations ranging from the Precambrian to more recent tectonic mountain-building events.

Uses & applications

Common varieties are used as industrial abrasives (sandpaper, waterjet cutting). Clear, well-colored specimens are used in jewelry and as birthstones. Highly valued by mineral collectors when found as well-formed crystals.

Geological facts

Garnets have been used as gemstones since the Bronze Age in ancient Egypt. Almandine is the most common member of the garnet group. Some specimens exhibit 'asterism' (a star-like light effect) due to rutile needle inclusions.

Field identification & locations

Identify in the field by its characteristic 12-sided (dodecahedral) crystal shape, high density, and lack of cleavage. Often found emerging from silver-grey schist rock or in river gravels as 'ruby sand.' Common locations include New York (USA), Brazil, India, and Sri Lanka.

Other mineral specimens

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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)]

mineral

Epidote

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

mineral