metamorphic
Gneiss
Gneiss
AI-generated identification · may be incorrectHardness of 6-7 on Mohs scale; displays distinct alternating light and dark mineral bands (gneissic banding); sub-to-vitreous luster.
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Physical properties
Hardness of 6-7 on Mohs scale; displays distinct alternating light and dark mineral bands (gneissic banding); sub-to-vitreous luster.
Formation & geological history
Formed under high-temperature and high-pressure metamorphic conditions, typically from pre-existing igneous or sedimentary rocks deep within the Earth's crust.
Uses & applications
Used primarily in the construction industry as crushed stone for road bases, building facades, and dimensional stone.
Geological facts
Gneiss contains some of the oldest known fragments of the Earth's crust, with certain zircon crystals dating back over 4 billion years.
Field identification & locations
Easily identifiable in the field by its characteristic zebra-like striping and foliation; found globally in ancient shield areas and core mountain ranges.
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