metamorphic
Gneiss
Gneiss
AI-generated identification · may be incorrectHardness of 6-7 on Mohs scale, characterized by distinct alternating light and dark mineral bands (foliation), dull to vitreous luster, and specific gravity around 2.6-2.9.
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Physical properties
Hardness of 6-7 on Mohs scale, characterized by distinct alternating light and dark mineral bands (foliation), dull to vitreous luster, and specific gravity around 2.6-2.9.
Formation & geological history
Formed through high-temperature and high-pressure regional metamorphism of pre-existing igneous or sedimentary rocks, typically occurring deep within the Earth's crust during continental collisions.
Uses & applications
Commonly used in the construction industry as crushed stone for roadbeds, building facades, and dimension stone.
Geological facts
Gneiss is among the oldest known rocks on Earth, with some formations dating back over 4 billion years.
Field identification & locations
Easily identified in the field by its striking banded appearance, known as gneissic banding, separating felsic and mafic minerals. Found globally in ancient shield areas.
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