metamorphic
Banded gneiss pebble
Foliated gneiss; likely quartz- and feldspar-rich, with dark mica or amphibole bands
AI-generated identification · may be incorrectGray and cream mineral bands with a fine-to-medium-grained, foliated texture; estimated Mohs hardness 6–7, vitreous to dull luster, and no obvious cleavage at pebble scale. Exact composition and specific gravity cannot be confirmed from the photo.
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Physical properties
Gray and cream mineral bands with a fine-to-medium-grained, foliated texture; estimated Mohs hardness 6–7, vitreous to dull luster, and no obvious cleavage at pebble scale. Exact composition and specific gravity cannot be confirmed from the photo.
Formation & geological history
Formed when pre-existing rock was recrystallized and compositionally banded under high heat and pressure during regional metamorphism. Gneisses occur in ancient continental crust, often billions of years old; the pebble’s age and source are unknown.
Uses & applications
Primarily a natural collectible or landscaping stone; gneiss is also used as dimension stone, aggregate, and paving material.
Geological facts
The alternating light and dark bands are gneissic foliation, typically caused by mineral segregation during metamorphism.
Field identification & locations
Look for persistent alternating mineral bands and a hard, crystalline texture; rounded edges suggest transport by water or ice. Gneiss is widespread in continental shields and mountain belts, but the photo cannot identify a specific locality.
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