Coarse-grained gneiss

Typically Mohs 6–7; gray, cream, tan, and brown with visible quartz and feldspar and darker mica-rich bands. Vitreous quartz luster, granular texture, and weak-to-strong foliation; no obvious cleavage as a whole rock.

Formed when granite or other felsic rock underwent high-grade regional metamorphism, commonly during Precambrian to Paleozoic mountain-building events. The image suggests weathered, banded or compositionally layered gneiss, though exact identification requires a fresh surface.

Used as crushed stone, aggregate, dimension stone, landscaping rock, and occasionally decorative slabs. Common specimens have modest collector value.

Quartz appears glassy or gray, feldspar is commonly white to pink, and biotite or hornblende forms dark flakes. Gneiss commonly records deep crustal pressures and temperatures above roughly 500–700°C.

Common in ancient continental shields and metamorphic mountain belts worldwide, including Scandinavia, Canada, the Appalachians, and India. Look for alternating light quartz-feldspar and dark mica/hornblende layers; a streak test and fresh fracture help distinguish it from granite.