metamorphic
Red garnet-bearing metamorphic rock
Almandine garnet (Fe₃Al₂Si₃O₁₂), likely in mica schist or quartz-rich matrix
AI-generated identification · may be incorrectGarnet crystals are reddish-orange, translucent to transparent, and commonly dodecahedral, with vitreous luster and no cleavage; hardness 6.5–7.5 Mohs and specific gravity about 3.9–4.3. The pale matrix appears quartz- and mica-rich, with possible chlorite or feldspar.
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Physical properties
Garnet crystals are reddish-orange, translucent to transparent, and commonly dodecahedral, with vitreous luster and no cleavage; hardness 6.5–7.5 Mohs and specific gravity about 3.9–4.3. The pale matrix appears quartz- and mica-rich, with possible chlorite or feldspar.
Formation & geological history
Garnet grew during medium- to high-grade regional metamorphism of aluminous sedimentary rock, typically during mountain building; the exact geological age cannot be determined from the image. Crystals formed as heat and pressure drove recrystallization and element exchange.
Uses & applications
Garnet is used as an abrasive and, when clear and attractive, as a gemstone; the matrix specimen is mainly valued by collectors. Such specimens are not generally used as construction stone.
Geological facts
The red grains are most consistent with almandine, though spessartine or mixed garnet cannot be excluded visually. Garnet’s lack of cleavage and equant crystal shape help distinguish it from ruby, tourmaline, and mica.
Field identification & locations
Look for hard, glassy red crystals that resist scratching and commonly form rhombic dodecahedra in schist or quartz. Common sources include India, Madagascar, Sri Lanka, Brazil, the United States, and Scandinavia.
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