Gneiss

Gneiss is a protolith of migmatite.

Properties
Rock group Metamorphic
Metamorphism type Regional
Metamorphic rock class Pelitic
Metabasic (mafic gneiss)
Marl
Granitic (granitic gneiss)
Protolith Schist
Igneous rocks such
as granite

Gneiss in Hand Sample

Paleoproterozoic gneiss from Clear Creek Canyon, CO

Archean-aged basement complex gneiss from the Wyoming Craton

Biotitemuscovitegarnet Maidens gneiss (note that that’s four separate links)

Augen gneiss

Big honkin’ augen in Paleoproterozoic augen gneiss from Clear Creek Canyon, CO

Augen gneiss from Shetland

Gneiss in Thin Section

Maidens gneiss, plane polars

Maidens gneiss, crossed polars

Sillimanitegarnet gneiss, plane polars

Sillimanitegarnet gneiss, crossed polars

Augen gneiss, plane polars

Augen gneiss, crossed polars

Biotite gneiss, plane polars

Biotite gneiss, crossed polars