mineral

Rough Garnet in Matrix

Almandine Garnet (Fe3Al2Si3O12)

Hardness: 6.5-7.5 on Mohs scale; Color: Deep red to reddish-brown (amber hues visible in backlit areas); Luster: Vitreous to resinous; Crystal structure: Isometric (dodecahedral); Cleavage: None, exhibits conchoidal fracture; Specific gravity: 3.5-4.3.

Hardness: 6
Luster: Vitreous to resinous

Identified March 29, 2026More mineral →

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Physical properties

Formation & geological history

Formed through regional metamorphism of clay-rich sedimentary rocks (like shale) under high pressure and temperature conditions. Typically found in mica schists or gneisses. Age varies depending on the metamorphic belt (e.g., Precambrian to Cenozoic).

Uses & applications

Common industrial uses include abrasives (sandpaper and water-jet cutting) due to its hardness. High-quality transparent specimens are used as gemstones in jewelry. Rough specimens are popular for amateur mineral collecting.

Geological facts

Garnets are one of the few minerals that are not enhanced by heat or radiation. Almandine, specifically, is the most common variety of garnet and has been used in jewelry for thousands of years, notably by ancient Romans and Greeks.

Field identification & locations

Identify in the field by its characteristic 12-sided crystal shape (if well-formed) and its unusual weight due to high iron content. Commonly found in metamorphic terrains such as the Adirondack Mountains (NY), Idaho, or worldwide in countries like Brazil and India. Collectors should look for distinct geometric faces protruding from a softer host rock.

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Sandstone (with potential mineral staining/concretions)

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