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Metamorphic rock

Gneiss

The highest grade of the foliated series; coarse-grained, with minerals separated into light (feldspar, quartz) and dark (amphibole) bands, and little or no mica. Parents include mudrock, sandstone, conglomerate and igneous rocks.

Gneiss hand samples and outcrop
Gneiss hand samples and outcrop. Karla Panchuk (2018), CC BY-SA 4.0. Source

Photos are hosted by their original sites and shown under their open licenses (CC BY, CC BY-SA, public domain or Open Government Licence). Click a photo for its source page.

More photos and thin sections

Alex Strekeisen: Augen gneiss

Other metamorphic rocks

Slate · Phyllite · Schist · Amphibolite · Marble · Quartzite · Hornfels · Migmatite

Sources

Panchuk, Physical Geology 10.3: Classification of Metamorphic Rocks