metamorphic
Gneiss
Gneiss
AI-generated identification · may be incorrectHardness of 6-7 on Mohs scale, characterized by distinct alternating light and dark compositional banding (gneissic banding), vitreous luster, and granular texture.
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Physical properties
Hardness of 6-7 on Mohs scale, characterized by distinct alternating light and dark compositional banding (gneissic banding), vitreous luster, and granular texture.
Formation & geological history
Formed by high-temperature and high-pressure regional metamorphism of pre-existing igneous or sedimentary rocks deep within the Earth's crust.
Uses & applications
Used primarily as dimension stone in construction, building facades, paving, and decorative landscaping.
Geological facts
Gneiss is one of the oldest common rock types on Earth, with some formations dating back over 4 billion years.
Field identification & locations
Easily identified in the field by its characteristic zebra-like alternating light quartz/feldspar and dark biotite/hornblende bands; found globally in ancient shield areas.
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