metamorphic
Gneiss
Metamorphic Gneiss
AI-generated identification · may be incorrectHardness of 6-7 on Mohs scale, characterized by distinctive 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 distinctive alternating light and dark compositional banding (gneissic banding), vitreous luster, and granular texture.
Formation & geological history
Formed through high-grade regional metamorphism of preexisting igneous or sedimentary rocks deep within the Earth's crust under intense heat and pressure.
Uses & applications
Used primarily as crushed stone in construction, dimension stone for buildings, and as decorative facing or paving material.
Geological facts
Some of the oldest known rock formations on Earth, dating back over 4 billion years, are composed of gneiss.
Field identification & locations
Easily identified in the field by its striking striped or banded appearance resulting from mineral segregation; commonly found in ancient continental shields.
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