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). Composed mainly of quartz, feldspar, mica, and amphibole.
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Physical properties
Hardness of 6-7 on Mohs scale, characterized by distinct alternating light and dark compositional bands (gneissic banding). Composed mainly of quartz, feldspar, mica, and amphibole.
Formation & geological history
Formed through high-grade regional metamorphism of preexisting igneous or sedimentary rocks under extreme heat and directed pressure.
Uses & applications
Used primarily in the construction industry as crushed stone for road bases, building facades, and decorative landscaping blocks.
Geological facts
Gneiss includes some of the oldest rocks found on Earth, dating back over 4 billion years in certain cratons. The distinctive banding results from mineral segregation under intense tectonic stress.
Field identification & locations
Identify by its zebra-like alternating light and dark mineral bands. Commonly found in ancient continental shields and mountain-building belts worldwide.
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