Meaning of augengneiss | Babel Free

Definitions

A type of metamorphic rock characterized by large, lenticular mineral grains or crystal aggregates that resemble "eyes" (called augen in German) embedded within a finer-grained matrix. These "eyes" are usually feldspar or quartz grains that have been deformed during metamorphism.

Examples

“The term ‘Augengneiss’ has a definite use in German petrography, and is properly used to denote those gneisses "in which single large felspar-masses (orthoclase), in form ranging from the blunt lenticular to the approximately spherical, occur, segregated from the matrix of the rock which possesses a schistose (schieferig) or coarse grained (flaserig) structure, and around which the mica-laminæ adhere."”

“Rocks of this migmatitic formation, having a smaller quantity of neosome, are augengneisses.”

“In the Canigou Massif the group’s metasediments together with the gneisses and the augengneisses were folded into a gigantic flat-lying isoclinal fold.”

CEFR level