metamorphic

Likely banded gneiss or mica-rich metamorphic pebble

Gneiss; composition likely quartz, feldspar, and biotite/muscovite mica

AI-generated identification · may be incorrect

Dark gray and white, strongly foliated/banded, with a dull to slightly sparkly luster; typical hardness is about 6–7 Mohs, nonmetallic, and cleavage occurs mainly in the mica grains. The photograph is too blurred for confident species-level identification.

Identified September 13, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when preexisting igneous or sedimentary rock underwent intense heat and pressure, producing mineral segregation and foliation; ages range from hundreds of millions to billions of years. This may be a naturally weathered landscaping or glacially transported pebble.

Uses & applications

Common gneiss is used as dimension stone, paving, aggregate, and decorative landscaping rock; attractive polished pieces are collected but are generally not gemstone grade.

Geological facts

The alternating light and dark bands reflect separated quartz/feldspar and mafic mica-rich minerals. Gneiss commonly records deep crustal metamorphism and may preserve evidence of multiple tectonic events.

Field identification & locations

Look for planar or swirled light-dark banding, visible mica sparkle, and a hard surface that resists scratching by a steel knife. Common in continental shields and glaciated regions, including Canada, Scandinavia, the northeastern United States, and many mountain belts.