metamorphic
Weathered mica-rich schist
Muscovite/biotite schist, likely quartz-bearing
AI-generated identification · may be incorrectVisible platy, reflective mica flakes in a foliated fabric; gray-brown to tan, dull to pearly luster, medium-grained, with probable quartz and feldspar. Mica hardness is about 2–3 Mohs, quartz about 7; schist has no single specific gravity or crystal structure.
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Physical properties
Visible platy, reflective mica flakes in a foliated fabric; gray-brown to tan, dull to pearly luster, medium-grained, with probable quartz and feldspar. Mica hardness is about 2–3 Mohs, quartz about 7; schist has no single specific gravity or crystal structure.
Formation & geological history
Formed when shale or another clay-rich sediment was buried, heated, and compressed during regional metamorphism, commonly producing strong mica foliation. Exact age cannot be determined from the photograph.
Uses & applications
Used mainly as decorative stone, landscaping material, and occasionally dimension stone; attractive mica-rich pieces are collected, but this specimen appears common rather than gem-grade.
Geological facts
The aligned mica flakes create schistosity and allow splitting along foliation. The dark rounded object above it appears to be a separate non-geological item, not part of the specimen.
Field identification & locations
Identify it by abundant sparkly mica plates and layered splitting, distinguishing it from granite (massive, nonfoliated) and slate (much finer-grained). Schist is plausible in the Papua New Guinea highlands near 9.4°S, 147.2°E, though local confirmation requires a fresh surface or testing.
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