metamorphic
Gneiss
Gneiss
AI-generated identification · may be incorrectHardness of 6-7 on Mohs scale, foliated texture with distinct light and dark compositional bands, vitreous to dull luster, and granular crystal structure.
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Physical properties
Hardness of 6-7 on Mohs scale, foliated texture with distinct light and dark compositional bands, vitreous to dull luster, and granular crystal structure.
Formation & geological history
Formed through high-grade regional metamorphism of pre-existing igneous or sedimentary rocks under intense heat and directional pressure.
Uses & applications
Used primarily as crushed stone in road construction, building foundations, and dimension stone for architectural facing.
Geological facts
Gneiss contains some of the oldest known rock material on Earth, dating back over 4 billion years in certain cratons.
Field identification & locations
Identify in the field by its striking zebra-like banding of alternating light and dark silicate minerals; found globally in ancient shield regions.
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