metamorphic
Gneiss
Gneiss
AI-generated identification · may be incorrectHardness of 6-7 on Mohs scale, characterized by distinct alternating light and dark compositional banding (gneissic banding). It has a vitreous to dull luster and a foliated texture.
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Physical properties
Hardness of 6-7 on Mohs scale, characterized by distinct alternating light and dark compositional banding (gneissic banding). It has a vitreous to dull luster and a foliated texture.
Formation & geological history
Formed through high-grade regional metamorphism of preexisting igneous or sedimentary rocks under intense heat and directional pressure, typically during mountain-building events.
Uses & applications
Used primarily in the construction industry as crushed stone for road bases, building facades, and dimension stone for landscaping and flooring.
Geological facts
Gneiss includes some of the oldest rocks found on Earth, with certain samples dating back over 4 billion years.
Field identification & locations
Easily identified in the field by its striking zebra-like banding of light quartz and feldspar alternating with dark biotite or amphibole bands.
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