![Garnet-bearing Schist (Almandine Garnet [Fe3Al2(SiO4)3] in Micaceous Schist) — metamorphic](https://media.rock.id/4f0ec920-fe4f-4eb7-b70c-80620cb5921d-compressed.jpg)
metamorphic
Garnet-bearing Schist
Almandine Garnet [Fe3Al2(SiO4)3] in Micaceous Schist
Hardness: 6.5-7.5 (garnets); Color: Deep reddish-brown to dark gray; Luster: Vitreous to sub-vitreous on garnets, pearly on matrix; Structure: Foliated matrix with euhedral dodecahedral crystals; Cleavage: None (garnets have conchoidal fracture).
- Hardness
- 6
- Color
- Deep reddish-brown to dark gray
- Luster
- Vitreous to sub-vitreous on garnets, pearly on matrix
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Physical properties
Hardness: 6.5-7.5 (garnets); Color: Deep reddish-brown to dark gray; Luster: Vitreous to sub-vitreous on garnets, pearly on matrix; Structure: Foliated matrix with euhedral dodecahedral crystals; Cleavage: None (garnets have conchoidal fracture).
Formation & geological history
Formed through regional metamorphism of clay-rich sedimentary rocks (shales) under high temperature and pressure conditions, often during mountain-building events. Geological age varies by locality but often Precambrian to Paleozoic.
Uses & applications
Abrasives (sandpaper, waterjet cutting), industrial filtering, gemstone for jewelry (January birthstone), and popular specimen for mineral collectors.
Geological facts
Garnets are index minerals used by geologists to determine the degree of metamorphism a rock has undergone. The Almandine variety is the most common member of the garnet group.
Field identification & locations
Identify by looking for characteristic 'soccer ball' shaped reddish crystals embedded in a flaky, mica-rich rock. Found commonly in the Appalachian Mountains, Alps, and Himalayas. Collectors should look for well-defined crystal faces.
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