metamorphic

Banded gneiss pebble

Quartz–feldspar gneiss, possibly with biotite or amphibole

AI-generated identification · may be incorrect

Rounded, tan-pink pebble with a dark mineral-rich band and faint foliation; likely quartz and feldspar with darker mica or amphibole. Quartz hardness is 7 and feldspar about 6; exact composition and specific gravity cannot be determined from the image.

Identified October 13, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when pre-existing rock was recrystallized under high heat and pressure, producing mineral banding; its precise age and source are not identifiable from the photo.

Uses & applications

Primarily a collecting specimen or decorative pebble; gneiss is also used as building and dimension stone.

Geological facts

Gneissic banding reflects the segregation of light and dark minerals during metamorphism.

Field identification & locations

Look for alternating pale quartz–feldspar and darker mineral bands, often with a foliated texture; similar pebbles occur in glacial deposits, river gravels, and regions underlain by metamorphic rocks.