mineral

Almandine Garnet

Almandine (Fe3Al2(SiO4)3)

Hardness: 7-7.5 (Mohs scale); Color: Deep red, brownish-red, to black; Luster: Vitreous to resinous; Crystal structure: Isometric/Cubic (often dodecahedral); Cleavage: None (conchoidal fracture); Specific gravity: 4.1-4.3

Hardness: 7-7
Color: Deep red, brownish-red, to black
Luster: Vitreous to resinous

Identified April 1, 2026More mineral →

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Physical properties

Formation & geological history

Formed during regional metamorphism of clay-rich sedimentary rocks (shales) into schists and gneisses. It can also occur in igneous rocks like granites and pegmatites. Found across various geological ages from Precambrian to Cenozoic.

Uses & applications

Used primarily as an abrasive (sandblasting, water-jet cutting, and sandpaper) due to its hardness. High-quality transparent specimens are used in jewelry as gemstones. Also valued for geological research to determine pressure/temperature history of rocks.

Geological facts

Almandine is the most common member of the garnet group. It is sometimes called 'Carbuncle' when cut as a cabochon. It remains a popular birthstone for January and is often found in large, well-formed crystals compared to other garnet types.

Field identification & locations

Identify in the field by its characteristic dodecahedral (12-sided) crystal shape, high harness, and deep red color. Frequently found embedded in mica schists. Common locations include New York (USA), India, Brazil, and Madagascar.