augen structure

augen structure

[′au̇·gən ‚strək·chər]
(petrology)
A structure found in some gneisses and granites in which certain of the constituents are squeezed into elliptic or lens-shaped forms and, especially if surrounded by parallel flakes of mica, resemble eyes.
References in periodicals archive ?
From base to top, these are (1) migmatitic gneiss, (2) augen gneiss characterized by a fairly constant blastomylonitic texture probably related to shear movements, and (3) intermediate gneiss that has preserved the augen structure but has apparently undergone slight migmatization.