metamorphic
Gneiss
Gneiss
AI-generated identification · may be incorrectHardness of 6-7 on the Mohs scale, characterized by distinct alternating light and dark compositional bands (gneissic banding) with a vitreous to dull luster.
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Physical properties
Hardness of 6-7 on the Mohs scale, characterized by distinct alternating light and dark compositional bands (gneissic banding) with a vitreous to dull luster.
Formation & geological history
Formed through high-grade regional metamorphism of preexisting igneous or sedimentary rocks under extreme heat and pressure, typically during mountain-building events.
Uses & applications
Used primarily in the construction industry as crushed stone for roadbeds, building facades, and dimension stone.
Geological facts
Some of the oldest known rocks on Earth, dating back over 4 billion years, are classified as gneiss.
Field identification & locations
Easily identified in the field by its striking zebra-like light and dark mineral bands, commonly found in ancient continental shields.
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