metamorphic
Mica-rich schist (probable muscovite schist)
Muscovite–quartz schist; commonly containing biotite, feldspar, and minor iron oxides
AI-generated identification · may be incorrectHardness is typically 2–3 for mica but about 6–7 for quartz; silvery-gold to brown, with a glittery pearly luster and strongly foliated texture. The elongated piece appears weathered and rounded, with visible platy mica grains; exact mineral proportions cannot be confirmed from one image.
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Physical properties
Hardness is typically 2–3 for mica but about 6–7 for quartz; silvery-gold to brown, with a glittery pearly luster and strongly foliated texture. The elongated piece appears weathered and rounded, with visible platy mica grains; exact mineral proportions cannot be confirmed from one image.
Formation & geological history
Formed when mica- and clay-rich sediment was buried, heated, and compressed during regional metamorphism, commonly from Precambrian to Paleozoic mountain-building events. Around 10.1°N, 2.5°W in Ghana/Burkina Faso, Precambrian Birimian metamorphic rocks make this identification plausible.
Uses & applications
Used locally as dimension stone, aggregate, landscaping material, and occasionally decorative stone; attractive mica-rich pieces are mainly collector specimens rather than gemstones.
Geological facts
The sparkle comes from countless reflective mica cleavage surfaces, not necessarily metallic minerals. Schistosity allows the rock to split along aligned mica layers.
Field identification & locations
Look for visible flakes that reflect light, planar foliation, and easy splitting or scratching of mica layers; a steel nail may scratch exposed mica but not quartz grains. Common in metamorphic belts worldwide, including West Africa.
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