metamorphic
Garnet-bearing schist or gneiss
Garnet-mica schist/gneiss; chiefly quartz, feldspar, mica, and almandine–pyrope garnet
AI-generated identification · may be incorrectCoarse, foliated, granular rock with pale quartz/feldspar and reddish-brown garnet porphyroblasts; vitreous garnet luster, Mohs hardness 6.5–7.5, quartz hardness 7, and probable mica cleavage. Exact identification would benefit from a fresh surface and hardness testing.
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Physical properties
Coarse, foliated, granular rock with pale quartz/feldspar and reddish-brown garnet porphyroblasts; vitreous garnet luster, Mohs hardness 6.5–7.5, quartz hardness 7, and probable mica cleavage. Exact identification would benefit from a fresh surface and hardness testing.
Formation & geological history
Formed when clay-rich sedimentary or igneous protoliths underwent medium- to high-grade regional metamorphism, commonly during mountain building; age depends on locality and cannot be determined from the image.
Uses & applications
Used mainly as a collector specimen and educational sample; garnet may be recovered as an abrasive, while comparable metamorphic stone can be used locally for aggregate or decorative material.
Geological facts
The red crystals are likely garnet, which commonly survives weathering because of its hardness. Distinct foliation and visible mica would favor schist; a more massive, banded texture would favor gneiss.
Field identification & locations
Look for planar mica alignment, scattered equant red garnets, and no vesicles or sedimentary layering; a streak, acid, and magnet test can help exclude alternatives. Common in metamorphic belts worldwide, including New England, the Appalachians, Scandinavia, India, and Madagascar.
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