metamorphic

Almandine Garnet

Almandine (Fe3Al2(SiO4)3)

AI-generated identification · may be incorrect

Hardness: 7-7.5 on the Mohs scale. Color: Dark red to brownish-black. Luster: Vitreous to resinous. Crystal structure: Isometric (dodecahedral). Cleavage: None. Specific gravity: 4.1-4.3.

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

Identified July 14, 2026More metamorphic →

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Physical properties

Hardness: 7-7.5 on the Mohs scale. Color: Dark red to brownish-black. Luster: Vitreous to resinous. Crystal structure: Isometric (dodecahedral). Cleavage: None. Specific gravity: 4.1-4.3.

Formation & geological history

Forms primarily in regional metamorphic rocks such as mica schists and gneisses, where heat and pressure recrystallize sediment-rich minerals. It can also be found in some igneous rocks like granites.

Uses & applications

Used widely as an abrasive (sandpaper, waterjet cutting), in jewelry as a gemstone, and as a common scientific indicator of metamorphic grade.

Geological facts

This specific dodecahedral shape (12-sided) is the classic natural crystal form for garnets. Almandine is the most common member of the garnet group.

Field identification & locations

Identify in the field by its distinct 12-sided crystal habit, high hardness, and density. Commonly found in metamorphic terrains such as the Adirondacks or the Alps.