metamorphic

Likely gneiss (rounded river-worn pebble)

Foliated quartz–feldspar gneiss, with mica and possibly amphibole

AI-generated identification · may be incorrect

Coarse, sparkly, gray rock with light and dark mineral grains; likely Mohs hardness 6–7. Quartz and feldspar have no obvious cleavage, while mica may split into flakes; exact composition cannot be confirmed from the image.

Identified October 14, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when pre-existing rock was recrystallized under high heat and pressure, commonly deep in continental crust. Gneisses occur across a wide range of geological ages.

Uses & applications

Gneiss is used as building and paving stone, aggregate, and decorative dimension stone; this small pebble is mainly suitable for collecting.

Geological facts

The contrasting mineral grains and possible weak banding are consistent with gneiss, though the photo does not show enough detail to distinguish it reliably from other coarse-grained rocks.

Field identification & locations

Look for interlocking, visibly distinct light and dark mineral bands or streaks; a rounded shape suggests water abrasion. Gneiss is widespread in ancient continental shields and mountain belts.