metamorphic
Quartz-bearing metamorphic rock, likely mica schist or gneiss fragment
Muscovite–biotite schist/gneiss with quartz and feldspar
AI-generated identification · may be incorrectGray, tan, and silvery foliation with sparkly mica and a prominent milky-gray quartz vein or lens; quartz has Mohs hardness 7, mica 2–3, and the specimen likely has moderate specific gravity around 2.7. Mica gives a flaky luster and the rock may split along foliation.
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Physical properties
Gray, tan, and silvery foliation with sparkly mica and a prominent milky-gray quartz vein or lens; quartz has Mohs hardness 7, mica 2–3, and the specimen likely has moderate specific gravity around 2.7. Mica gives a flaky luster and the rock may split along foliation.
Formation & geological history
Formed when shale or other feldspathic sediment was buried, heated, and compressed during regional metamorphism, likely Paleozoic or older depending on locality. Quartz veins formed when hot, silica-rich fluids entered fractures during or after metamorphism.
Uses & applications
Primarily a collecting specimen; related schists and gneisses are used as decorative stone, aggregate, and occasionally building stone, though strong foliation limits durability. Quartz-rich pieces may be attractive cabinet specimens but are not normally gem-quality.
Geological facts
The silvery reflective flakes are probably muscovite, while darker flakes may be biotite; the rounded shape appears naturally weathered or water-worn. A glassy quartz vein cutting foliation is a useful diagnostic feature.
Field identification & locations
Look for aligned mica flakes, banding or foliation, quartz-rich patches, and uneven splitting; it should scratch glass where exposed quartz is present. Common in regional metamorphic belts worldwide, including the Appalachians, Canadian Shield, and European mountain ranges.
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