metamorphic
Gneiss
Gneiss
AI-generated identification · may be incorrectHardness of 6-7 on Mohs scale, characterized by distinct alternating light and dark compositional bands (gneissic banding) with a vitreous to sub-resinous luster.
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Physical properties
Hardness of 6-7 on Mohs scale, characterized by distinct alternating light and dark compositional bands (gneissic banding) with a vitreous to sub-resinous luster.
Formation & geological history
Formed through high-grade regional metamorphism of pre-existing igneous or sedimentary rocks under intense heat and directed pressure.
Uses & applications
Used primarily as crushed stone for building construction, road aggregate, and occasionally as architectural facing stone.
Geological facts
Gneiss can contain some of the oldest mineral fragments discovered on Earth, dating back over 4 billion years.
Field identification & locations
Easily identified by its zebra-like striping of light quartz/feldspar and dark biotite/amphibole bands, found in ancient shield areas worldwide.
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