metamorphic

Veined gneiss

Felsic to mafic banded gneiss, chiefly quartz–feldspar–biotite/hornblende

AI-generated identification · may be incorrect

Typically medium- to coarse-grained, gray-green, with a granular to weakly foliated texture and contrasting white quartz/feldspar veins. Hardness is about 6–7 Mohs; vitreous to dull luster, no consistent cleavage as a whole, and specific gravity roughly 2.65–2.85.

Identified September 11, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when preexisting igneous or sedimentary rock underwent high-grade regional metamorphism, producing recrystallization and mineral banding; commonly Precambrian to Paleozoic. The white material is likely quartz or feldspar-rich veining introduced during deformation.

Uses & applications

Used as crushed stone, aggregate, dimension stone, landscaping rock, and occasionally as polished architectural stone. This coarse field specimen has modest collector value.

Geological facts

Gneiss commonly preserves evidence of intense continental collision and deep-crustal heating. Its light and dark bands reflect mineral segregation during metamorphism rather than original sedimentary layering.

Field identification & locations

Identify it by alternating light and dark mineral bands, coarse interlocking grains, and resistance to scratching; quartz veins may scratch glass. Common in ancient continental shields and mountain belts; exact locality requires a fresh surface and field context.