metamorphic
Gneiss
Gneiss
AI-generated identification · may be incorrectHardness 6-7 on the Mohs scale, characterized by distinct alternating light and dark compositional banding. It features a coarse-grained texture with a vitreous to dull luster.
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Physical properties
Hardness 6-7 on the Mohs scale, characterized by distinct alternating light and dark compositional banding. It features a coarse-grained texture with a vitreous to dull luster.
Formation & geological history
Formed through high-grade regional metamorphism of pre-existing igneous or sedimentary rocks under intense heat and pressure, typically during mountain-building events.
Uses & applications
Used primarily as crushed stone for building construction, road aggregates, and occasionally as dimension stone for facing and paving.
Geological facts
Gneiss includes some of the oldest known rocks on Earth, with certain formations dating back over 4 billion years. The distinctive bands are often called gneissic banding.
Field identification & locations
Identify by its zebra-like alternating light and dark mineral bands, commonly found in ancient continental shields and eroded mountain belts. It is widespread globally.
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