metamorphic
Dark foliated metamorphic rock, probably schist
Mica schist, likely quartz–muscovite/biotite schist
AI-generated identification · may be incorrectGray-green, fine- to medium-grained, weakly shiny from aligned mica; likely Mohs 2–7 depending on grains, with mica cleavage and quartz/feldspar hardness. The rounded shape appears naturally weathered or water-worn; individual crystals are not clear enough for certainty.
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Physical properties
Gray-green, fine- to medium-grained, weakly shiny from aligned mica; likely Mohs 2–7 depending on grains, with mica cleavage and quartz/feldspar hardness. The rounded shape appears naturally weathered or water-worn; individual crystals are not clear enough for certainty.
Formation & geological history
Formed when shale or another clay-rich sediment was subjected to regional heat and pressure, producing mica alignment and foliation. Its precise age cannot be determined from the photograph; metamorphic rocks in Yemen may range from Precambrian basement to younger tectonic units.
Uses & applications
Used locally as building or paving stone and occasionally as decorative material, but this ordinary specimen has little commercial value.
Geological facts
The reflective specks are probably mica rather than metallic ore. The reported location in Yemen is geologically plausible for metamorphic basement rocks, although a dark weathered basalt or serpentinite remains possible without testing.
Field identification & locations
Look for planar splitting, glittering mica flakes, and bands or foliation; a streak, hardness test, and fresh broken surface would help distinguish schist from basalt or serpentinite. Commonly found in metamorphic terranes and stream gravels.
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