gemstone
Almandine Garnet
Almandine (Fe3Al2(SiO4)3)
Hardness: 6.5 to 7.5 on the Mohs scale; Color: Deep red, brownish-red, or dark red; Luster: Vitreous to resinous; Crystal structure: Isometric (cubic); Cleavage: None, exhibits conchoidal fracture; Specific gravity: 3.9 to 4.3
- Hardness
- 6
- Color
- Deep red, brownish-red, or dark red
- Luster
- Vitreous to resinous
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Physical properties
Hardness: 6.5 to 7.5 on the Mohs scale; Color: Deep red, brownish-red, or dark red; Luster: Vitreous to resinous; Crystal structure: Isometric (cubic); Cleavage: None, exhibits conchoidal fracture; Specific gravity: 3.9 to 4.3
Formation & geological history
Forms primarily in metamorphic rocks such as mica schists and gneisses through regional metamorphism, as well as in some igneous rocks like granite pegmatites.
Uses & applications
Widely used in jewelry as a faceted or cabochon gemstone, as an abrasive in waterjet cutting and sandblasting, and by collectors.
Geological facts
Almandine is the most common and widespread of the garnet group minerals, often historically referred to along with other red gems as 'carbuncle'.
Field identification & locations
Identified by its deep red color, characteristic isometric crystal habit or rounded crystal shapes (dodecahedrons/trapezoids), and high hardness. Found worldwide including India, Brazil, Madagascar, and the USA.
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