metamorphic
Gneiss
Foliated Metamorphic Rock
AI-generated identification · may be incorrectHardness of 6-7 on the Mohs scale, characterized by distinct alternating light and dark compositional banding. Displays a vitreous to dull luster with a massive, crystalline structure.
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Physical properties
Hardness of 6-7 on the Mohs scale, characterized by distinct alternating light and dark compositional banding. Displays a vitreous to dull luster with a massive, crystalline structure.
Formation & geological history
Formed through high-grade regional metamorphism of pre-existing igneous or sedimentary rocks under intense heat and directional pressure deep within the Earth's crust.
Uses & applications
Commonly used in the construction industry as crushed stone for road bases, building facades, and durable dimensional stone slabs.
Geological facts
Some of the oldest known rocks on Earth, dating back over 4 billion years, are composed of Acasta Gneiss found in Canada.
Field identification & locations
Identified in the field by its striking zebra-like compositional banding known as gneissic banding. Found globally in ancient shield areas and mountain core regions.
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