metamorphic
Likely chlorite-bearing schist (possibly greenschist)
Chlorite–quartz–mica schist; commonly contains muscovite/biotite and feldspar
AI-generated identification · may be incorrectUsually greenish-black to gray, with a strong foliated texture and silky to dull luster; chlorite is Mohs 2–2.5, quartz 7, and mica 2–3. The slab appears layered and micaceous, though image-based identification is provisional.
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Physical properties
Usually greenish-black to gray, with a strong foliated texture and silky to dull luster; chlorite is Mohs 2–2.5, quartz 7, and mica 2–3. The slab appears layered and micaceous, though image-based identification is provisional.
Formation & geological history
Formed when clay-rich sedimentary or volcanic rock underwent low- to medium-grade regional metamorphism, commonly during mountain building. Such rocks may range from Precambrian to younger Paleozoic or Mesozoic ages.
Uses & applications
Used locally as decorative stone, landscaping rock, wall stone, and occasionally roofing or paving material; attractive polished pieces may be collected but are not generally jewelry-grade.
Geological facts
Green coloration commonly reflects chlorite, epidote, or actinolite produced under greenschist-facies conditions. Foliation results from aligned mica and chlorite minerals.
Field identification & locations
Look for planar splitting, glittering mica flakes, and green-black mineral bands; a glass scratch test can distinguish quartz-rich portions. Common in metamorphic belts worldwide, including the Appalachians, Alps, and Pacific coastal ranges.
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