metamorphic

Banded gneiss

Foliated gneiss, likely quartz–feldspar–mica gneiss

AI-generated identification · may be incorrect

Coarse-grained, irregular light and dark mineral bands; likely quartz and feldspar with dark biotite or amphibole. Typical hardness is 6–7 Mohs; minerals have vitreous to dull luster and interlocking crystals, without consistent rock-wide cleavage. Exact composition cannot be confirmed from the image alone.

Identified September 23, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when pre-existing igneous or sedimentary rock was recrystallized and segregated into bands under high heat and pressure, often deep in continental crust. Gneisses occur across a wide range of geological ages.

Uses & applications

Used as dimension stone, landscaping rock, aggregate, and occasionally decorative slabs; attractive pieces are collected.

Geological facts

Gneissic banding reflects mineral separation during metamorphism and is not necessarily original sedimentary layering.

Field identification & locations

Look for coarse, alternating pale quartz–feldspar and darker mineral bands; unlike schist, gneiss generally has less platy, less pronounced foliation. Common in ancient continental shields and mountain belts; the photograph does not establish a specific locality.