metamorphic
Gneiss
Gneiss
AI-generated identification · may be incorrectHardness of 6-7 on the Mohs scale with a banded or foliated texture, typically displaying alternating light and dark mineral layers. It has a vitreous to dull luster and a crystalline structure.
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Physical properties
Hardness of 6-7 on the Mohs scale with a banded or foliated texture, typically displaying alternating light and dark mineral layers. It has a vitreous to dull luster and a crystalline structure.
Formation & geological history
Formed by high-temperature and high-pressure regional metamorphic processes altering pre-existing igneous or sedimentary rocks deep within the Earth's crust.
Uses & applications
Used primarily in the construction industry as crushed stone for roadbeds, building facades, and dimension stone for landscaping.
Geological facts
Gneiss contains some of the oldest known rock material on Earth, with certain zircons found within it dating back over 4 billion years.
Field identification & locations
Easily identified in the field by its distinct alternating light-colored quartz/feldspar bands and dark-colored biotite/amphibole bands. Commonly found in ancient continental shields.
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