metamorphic
Gneiss
Gneiss
AI-generated identification · may be incorrectHardness 6-7 on Mohs scale, characterized by distinct alternating light and dark compositional banding. It exhibits a granular texture and dull to sub-vitreous luster.
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Physical properties
Hardness 6-7 on Mohs scale, characterized by distinct alternating light and dark compositional banding. It exhibits a granular texture and dull to sub-vitreous luster.
Formation & geological history
Formed through high-grade regional metamorphism of pre-existing igneous or sedimentary rocks under extreme heat and pressure, typically over hundreds of millions of years.
Uses & applications
Used primarily in the construction industry as crushed stone for road base, building facades, and dimension stone.
Geological facts
Gneiss contains some of the oldest known mineral fragments on Earth, with zircon crystals within it dating back over 4 billion years.
Field identification & locations
Easily identified by its characteristic zebra-like banding known as gneissic banding, commonly found in deeply eroded ancient mountain belts and continental shields.
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