metamorphic
Quartz-rich metamorphic fragment (likely mica schist)
Mica schist, probably muscovite–quartz schist
AI-generated identification · may be incorrectLikely composed mainly of quartz and platy mica, with minor feldspar or sulfides. Visible sparkly, flaky foliation; hardness about 2–2.5 for mica and 7 for quartz, vitreous to pearly luster, and poor cleavage overall but perfect mica cleavage.
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Physical properties
Likely composed mainly of quartz and platy mica, with minor feldspar or sulfides. Visible sparkly, flaky foliation; hardness about 2–2.5 for mica and 7 for quartz, vitreous to pearly luster, and poor cleavage overall but perfect mica cleavage.
Formation & geological history
Formed when clay-rich sedimentary rock was subjected to heat and directed pressure during regional metamorphism, commonly during mountain building. Its exact geological age cannot be determined from the image.
Uses & applications
Used locally as decorative stone, landscaping material, and occasionally in building stone; attractive pieces are collected but are generally not jewelry-grade.
Geological facts
The glitter comes from aligned mica flakes reflecting light, while quartz forms harder, glassier grains. It may resemble phyllite, gneiss, or ore-bearing rock without a fresh surface or testing.
Field identification & locations
Common in metamorphic mountain belts worldwide, including the Appalachians, Alps, and Himalayas. Check for strong layering, mica flakes that peel, a glassy quartz component, and a streak that is generally white or pale; an acid test is not diagnostic.
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