Rock Identifier
Garnet (specifically Almandine or Pyrope) (Almandine (Fe3Al2Si3O12) or Pyrope (Mg3Al2Si3O12)) — mineral
mineral

Garnet (specifically Almandine or Pyrope)

Almandine (Fe3Al2Si3O12) or Pyrope (Mg3Al2Si3O12)

Hardness: 6.5–7.5 on Mohs scale; Color: Deep dark red to reddish-brown; Luster: Vitreous (glassy); Crystal structure: Isometric (dodecahedron); Cleavage: None; Specific gravity: 3.5–4.3

Hardness
6
Color
Deep dark red to reddish-brown
Luster
Vitreous (glassy)
Identified More mineral

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Physical properties

Hardness: 6.5–7.5 on Mohs scale; Color: Deep dark red to reddish-brown; Luster: Vitreous (glassy); Crystal structure: Isometric (dodecahedron); Cleavage: None; Specific gravity: 3.5–4.3

Formation & geological history

Formed primarily in metamorphic rocks like mica schists and gneisses through heat and pressure, or in some igneous rocks. They are found in geological environments ranging from the Precambrian to recent alluvial deposits.

Uses & applications

Commonly used in jewelry as gemstones (birthstone for January), and industrially as an abrasive for sandblasting and water-jet cutting due to its hardness and sharp fracture edges.

Geological facts

Garnets were used in jewelry as far back as 3100 B.C. in Egypt. They were popular in the Victoria Era to create 'Bohemian garnet' jewelry. Because of their durability, they are one of the few gemstones found in river sediments (placer deposits).

Field identification & locations

Identify in the field by their characteristic dodecahedral (12-sided) crystal shape, high specific gravity, and lack of cleavage. Common locations include India, Madagascar, Sri Lanka, and the United States (notably New York and Idaho).