metamorphic

Weathered gray gneiss

Quartz–feldspar–mica gneiss

AI-generated identification · may be incorrect

Medium- to coarse-grained, gray, with weakly visible light/dark banding and a locally sparkly mica-rich surface. Typical hardness is about 6–7 Mohs; quartz and feldspar give vitreous to dull luster, while mica shows platy cleavage; specific gravity is roughly 2.6–2.8.

Identified September 17, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when granite or another felsic protolith was subjected to high temperature and pressure, producing compositional segregation and foliation. Commonly Precambrian to Paleozoic, though gneiss occurs in rocks of many ages.

Uses & applications

Used as dimension stone, architectural cladding, paving, countertops, aggregate, and landscape stone; attractive polished pieces may be collected, but this weathered outcrop has little commercial value.

Geological facts

The image most strongly suggests gneiss, although heavy weathering and limited exposure make exact identification uncertain; it could locally grade into granitic or schistose rock.

Field identification & locations

Look for alternating quartz/feldspar-rich light bands and darker biotite- or amphibole-rich bands, plus a tendency to split along foliation. Common in continental shields and deeply exposed mountain belts, including Canada, Scandinavia, the eastern United States, India, and Australia.