metamorphic
Banded gneiss (water-worn pebble)
Quartz–feldspar gneiss, with likely mica; exact mineralogy cannot be confirmed from the photo
AI-generated identification · may be incorrectPale cream, pink, and gray with irregular streaks of darker minerals; coarse crystalline, foliated/banded texture and a dull, weathered surface. Typical constituent hardness is about 6–7 Mohs; gneiss has no single crystal structure or specific gravity.
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Physical properties
Pale cream, pink, and gray with irregular streaks of darker minerals; coarse crystalline, foliated/banded texture and a dull, weathered surface. Typical constituent hardness is about 6–7 Mohs; gneiss has no single crystal structure or specific gravity.
Formation & geological history
Formed when pre-existing igneous or sedimentary rock was recrystallized under high heat and pressure, commonly deep in the continental crust; gneisses range from Archean to recent geologic ages.
Uses & applications
Gneiss is used as dimension stone, paving, landscaping aggregate, and decorative stone; this rounded pebble is chiefly a collecting or display specimen.
Geological facts
Its light-and-dark mineral segregation reflects metamorphic banding; rounding indicates prolonged abrasion during transport by water or ice.
Field identification & locations
Look for interleaved light quartz/feldspar-rich and darker mineral-rich bands, rather than the distinct grains of typical granite. Gneiss occurs in ancient continental shields and mountain belts worldwide; the image alone cannot determine its precise locality.
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