metamorphic

Gneiss

Metamorphic Gneiss

AI-generated identification · may be incorrect

Hardness 6-7 on Mohs scale, earthy to vitreous luster, banded or foliated texture, gray to reddish-brown coloration due to iron-oxide staining, composed mainly of quartz and feldspar

Identified July 24, 2026More metamorphic →

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Physical properties

Hardness 6-7 on Mohs scale, earthy to vitreous luster, banded or foliated texture, gray to reddish-brown coloration due to iron-oxide staining, composed mainly of quartz and feldspar

Formation & geological history

Formed under high-grade regional metamorphism subjecting original igneous or sedimentary rocks to intense heat and pressure deep within Earth's crust

Uses & applications

Used as crushed stone in road construction, building facing, landscaping, and decorative stone work

Geological facts

Gneiss is one of the oldest rock types on Earth; the Acasta Gneiss in Canada is dated to over 4 billion years old

Field identification & locations

Identified by distinct alternating light and dark mineral bands and coarse texture. Commonly found in mountainous regions and exposed continental shields worldwide