metamorphic
Gneiss
Orthogneiss / Paragneiss
AI-generated identification · may be incorrectHardness of 6-7 on Mohs scale, distinct alternating light and dark compositional banding (gneissic banding), vitreous to dull luster, foliated crystal structure.
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Physical properties
Hardness of 6-7 on Mohs scale, distinct alternating light and dark compositional banding (gneissic banding), vitreous to dull luster, foliated crystal structure.
Formation & geological history
Formed through high-grade regional metamorphism of pre-existing igneous or sedimentary rocks under extreme heat and pressure, typically during mountain-building events.
Uses & applications
Used primarily as dimension stone in construction, building facades, paving, and decorative landscaping.
Geological facts
Gneiss contains some of the oldest known rock material on Earth, with certain zircons found within gneiss dating back over 4 billion years.
Field identification & locations
Identified easily by its characteristic zebra-like alternating light and dark mineral bands; commonly found in ancient cratons and shield areas worldwide.
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