metamorphic
Garnet-bearing metamorphic rock, likely garnet schist or amphibolite
Almandine garnet (Fe₃Al₂Si₃O₁₂) in mica- or amphibole-rich matrix
AI-generated identification · may be incorrectDark gray to black, coarse and foliated, with reddish-brown garnet crystals; garnet hardness is about 6.5–7.5 Mohs, vitreous luster, cubic crystal system, and no cleavage. The surrounding matrix is softer and may show mica or amphibole cleavage.
Identified More metamorphic →
Explore Garnet-bearing metamorphic rock, likely garnet schist or amphibolite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Dark gray to black, coarse and foliated, with reddish-brown garnet crystals; garnet hardness is about 6.5–7.5 Mohs, vitreous luster, cubic crystal system, and no cleavage. The surrounding matrix is softer and may show mica or amphibole cleavage.
Formation & geological history
Formed when aluminous, iron-rich sedimentary or igneous rock was subjected to moderate-to-high heat and pressure during regional metamorphism, commonly during mountain building. Garnet growth may date from Paleozoic to Precambrian metamorphic events, depending on locality.
Uses & applications
Used primarily as a collectible specimen; garnet is also an abrasive and gemstone, while the host rock may be used locally as decorative stone or aggregate.
Geological facts
The red grains are probably almandine garnet, a common metamorphic index mineral that indicates increasing metamorphic grade. Exact identification requires a close inspection or testing of the matrix.
Field identification & locations
Common in metamorphic belts worldwide, including the Appalachians, New England, Scandinavia, India, and the western United States. Look for hard red-brown grains embedded in visibly layered mica schist or dark amphibolite; a streak, hardness, and density test can confirm garnet.
More like this
