metamorphic
Banded Gneiss
Gneiss (Metamorphic Rock)
Hardness: 6-7 on Mohs scale; Color: Grey matrix with white/cream bands; Luster: Dull to pearly; Structure: Foliated with distinct compositional banding (gneissic banding); Specific Gravity: 2.6-2.9
- Hardness
- 6-7 on Mohs scale
- Color
- Grey matrix with white/cream bands
- Luster
- Dull to pearly
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
Hardness: 6-7 on Mohs scale; Color: Grey matrix with white/cream bands; Luster: Dull to pearly; Structure: Foliated with distinct compositional banding (gneissic banding); Specific Gravity: 2.6-2.9
Formation & geological history
Formed through high-grade regional metamorphism of pre-existing igneous or sedimentary rocks. High temperature and pressure cause minerals to segregate into bands. Often associated with Precambrian orogenic belts.
Uses & applications
Used as building stone, decorative landscaping rock, crushed stone for road construction, and occasionally for high-end countertops or grave markers.
Geological facts
Gneiss is one of the oldest rock types on Earth; the Acasta Gneiss in Canada is approximately 4 billion years old. The banding represents extreme deformation where the rock flowed like plastic.
Field identification & locations
Identify by looking for distinct layers (bands) of different minerals that are often folded or wavy. Found in mountainous regions, riverbeds, and glacial deposits. Common in the Canadian Shield and Appalachian Mountains.
More like this
