metamorphic
Banded gneiss
Foliated gneiss, likely quartz–feldspar–mica-rich; exact mineral composition cannot be confirmed from the image
AI-generated identification · may be incorrectGray, tan, and dark wavy bands with a coarse, crystalline texture and no obvious cleavage. Typical constituent minerals—quartz, feldspar, and mica—have Mohs hardnesses of about 2–7; gneiss commonly has a specific gravity near 2.6–2.9.
Identified More metamorphic →
Explore Banded gneiss in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Gray, tan, and dark wavy bands with a coarse, crystalline texture and no obvious cleavage. Typical constituent minerals—quartz, feldspar, and mica—have Mohs hardnesses of about 2–7; gneiss commonly has a specific gravity near 2.6–2.9.
Formation & geological history
Formed when pre-existing rock was recrystallized and segregated into mineral bands under high heat and pressure deep in Earth’s crust. Gneiss occurs across many geological ages; this specimen’s age cannot be determined visually.
Uses & applications
Commonly used as dimension stone, paving, landscaping stone, and decorative material; small pieces are mainly collected or displayed.
Geological facts
The alternating light and dark bands are called gneissic banding and reflect mineral separation during metamorphism.
Field identification & locations
Look for coarse, interlocking grains and distinct, wavy light-and-dark bands; unlike sedimentary layers, the bands are recrystallized. Gneiss is widespread in ancient continental shields and mountain belts worldwide.
More like this
Other metamorphic specimens
Nephrite Jade
Nephrite
Mineral/Rock
Amphibolite
Amphibolite
metamorphic
Rhodonite
Manganese Silicate (Mn, Fe, Mg, Ca)SiO3
mineral
Rhodonite
(Mn,Fe,Mg,Ca)SiO3
mineral
Greenschist
Greenschist (containing Chlorite, Actinolite, and Epidote)
metamorphic
Garnet
Garnet group: X3Y2(SiO4)3 (commonly Almandine-Pyrope series)
mineral