metamorphic
Gneiss
Gneiss
AI-generated identification · may be incorrectHardness of 6-7 on Mohs scale, characterized by distinct alternating light and dark mineral bands with a foliated structure and vitreous luster.
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Physical properties
Hardness of 6-7 on Mohs scale, characterized by distinct alternating light and dark mineral bands with a foliated structure and vitreous luster.
Formation & geological history
Formed through high-grade regional metamorphism of pre-existing igneous or sedimentary rocks under extreme heat and directed pressure deep within the Earth's crust.
Uses & applications
Commonly used in the construction industry as crushed stone for road bases, building facades, and dimension stone.
Geological facts
Gneiss contains some of the oldest known rock material on Earth, with certain zircons found within it dating back over 4 billion years.
Field identification & locations
Easily identified in the field by its striking compositional banding, known as gneissic banding, separating quartz and feldspar from dark minerals like biotite.
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