metamorphic

Banded gneiss pebble

Gneiss, a foliated metamorphic rock composed mainly of quartz, feldspar, and mica or amphibole

AI-generated identification · may be incorrect

Rounded gray-and-white pebble with coarse, wavy compositional banding and a dull to slightly sparkly surface. Typical minerals have Mohs hardness around 6–7; the bands reflect aligned or segregated mineral grains rather than cleavage.

Identified October 4, 2026More metamorphic →

Explore Banded gneiss pebble in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Forms when pre-existing igneous or sedimentary rocks undergo high-grade heat and pressure, commonly deep in continental crust. Gneisses include rocks billions of years old as well as younger examples; this pebble’s age cannot be determined from the image.

Uses & applications

Used as decorative stone, landscaping aggregate, and building stone; this small rounded specimen is primarily suitable for collecting or display.

Geological facts

Gneissic banding develops as minerals recrystallize and separate into light- and dark-colored layers during metamorphism.

Field identification & locations

The alternating pale and dark bands and granular texture support identification as gneiss; rounding suggests transport by water or ice. Gneiss occurs widely in ancient continental shields and mountain belts.