metamorphic
Quartz-bearing metamorphic rock, likely mica schist
Mica schist with quartz; commonly muscovite/biotite mica and SiO₂ quartz
AI-generated identification · may be incorrectCoarse, foliated texture with dark reflective mica and white-gray quartz; mica has Mohs hardness 2–3 and quartz 7. Luster is mainly vitreous on quartz and pearly to submetallic on mica; cleavage is excellent in mica and poor in quartz.
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Physical properties
Coarse, foliated texture with dark reflective mica and white-gray quartz; mica has Mohs hardness 2–3 and quartz 7. Luster is mainly vitreous on quartz and pearly to submetallic on mica; cleavage is excellent in mica and poor in quartz.
Formation & geological history
Formed when clay-rich sedimentary rock underwent regional metamorphism, typically during mountain building, causing mica alignment and quartz recrystallization. The specimen’s exact geological age cannot be determined from the image.
Uses & applications
Used locally as decorative stone, aggregate, and occasionally landscaping material; attractive pieces may be collected, but it is generally unsuitable for high-wear countertops because foliation causes splitting.
Geological facts
The bright white grains are probably quartz, while the dark, flaky grains are biotite or graphite-bearing mica. Its layered fabric reflects directed pressure and heat rather than simple cooling from magma.
Field identification & locations
Common in metamorphic mountain belts such as the Appalachians, New England, Colorado, and the Alps. Identify it by visible foliation, glittering mica flakes, and hard quartz grains; a steel scratch test should mark mica but not quartz.
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