metamorphic

Tumbled banded gneiss

Quartz–feldspar–mica gneiss

AI-generated identification · may be incorrect

Coarse, irregularly banded gray, cream, and dark material with a matte to weakly polished luster; likely Mohs 6–7. Composed mainly of quartz and feldspar with biotite/hornblende; foliation is visible as dark and light bands, though the rounded surface obscures cleavage.

Identified September 1, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed by high-grade regional metamorphism of granite or sedimentary protoliths, typically during Precambrian to Paleozoic mountain-building. The specimen appears naturally weathered or tumbled rather than freshly fractured.

Uses & applications

Used as decorative stone, aggregate, landscaping rock, and occasionally in countertops or cabochons. Common pieces have modest collector value.

Geological facts

Gneiss commonly preserves alternating mineral bands produced by recrystallization and segregation under intense heat and pressure. It can resemble granite, but its streaky foliation distinguishes it.

Field identification & locations

Identify it by coarse interlocking grains and continuous light–dark banding; a glassy quartz-rich surface and feldspar grains support the identification. Common worldwide, especially in ancient continental shields and mountain belts.