metamorphic
Quartz-rich metamorphic rock, possibly mica schist
Muscovite–biotite schist with quartz; exact identification requires testing
AI-generated identification · may be incorrectVisible silvery, flaky mica and gray translucent quartz suggest schist. Hardness is variable: mica 2–3 Mohs, quartz 7; pearly to vitreous luster, foliated texture, and likely specific gravity around 2.7–2.9.
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Physical properties
Visible silvery, flaky mica and gray translucent quartz suggest schist. Hardness is variable: mica 2–3 Mohs, quartz 7; pearly to vitreous luster, foliated texture, and likely specific gravity around 2.7–2.9.
Formation & geological history
Formed when shale or another clay-rich sediment was subjected to elevated pressure and temperature during regional metamorphism, commonly during mountain building. Its precise geological age cannot be determined from the photograph.
Uses & applications
Used locally as decorative stone, aggregate, or landscaping material; attractive mica-rich pieces are collected, but this specimen is unlikely to have significant gem value.
Geological facts
The glittering flakes are probably mica, which splits into thin elastic sheets; quartz grains provide the harder, glassier portions.
Field identification & locations
Identify it by its planar foliation, sparkly mica flakes, and quartz-rich gray body; schist commonly occurs in metamorphic mountain belts worldwide, including the Appalachians, Rockies, Alps, and Himalayas. A streak, hardness, and thin-section test would confirm the minerals.
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