metamorphic
Banded Gneiss
Gneiss
Hardness: 6-7 on Mohs scale; Color: Greenish and white alternating bands; Luster: Vitreous to dull; Crystal structure: Foliated, granular texture with distinct compositional banding (gneissic banding).
- Hardness
- 6-7 on Mohs scale
- Color
- Greenish and white alternating bands
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Greenish and white alternating bands; Luster: Vitreous to dull; Crystal structure: Foliated, granular texture with distinct compositional banding (gneissic banding).
Formation & geological history
Formed under high-temperature and high-pressure metamorphic conditions, typically transforming from preexisting igneous rocks (like granite) or sedimentary rocks deep within the Earth's crust, often during continental collisions.
Uses & applications
Used primarily as dimension stone, crushed stone for construction, architectural facing, and sometimes as a decorative landscape rock.
Geological facts
Gneiss contains some of the oldest rocks found on Earth, with certain formations dating back over 4 billion years.
Field identification & locations
Easily identified by its alternating light and dark mineral bands (gneissic banding) which are coarser than those found in schist. Found in ancient shields and core mountain ranges worldwide.
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