augengneiss

English

Etymology

From German Augen + gneiss

Pronunciation

IPA^(key): /ˈaʊ̯ɡənˌnaɪ̯sɪz/

Noun

augengneiss (plural augengneisses)

1. 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.
   • 1889, A. IRVING, CHEMICAL AND PHYSICAL STUDIES int the METAMORPHISM of ROCKS based on A THESIS (WITH APPENDICES) WRITTEN FOR THE DOCTORATE IN SCIENCE IN THE UNIVERSITY OF LONDON., page 67:

     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."

   • 1964, Bruno Zanettin, Geology and Pertrology of Haramosh-mango Gusor Area (Italian Expeditions to the Karakorum (K²) and Hindu Kush SCIENTIFIC REPORTS; III - Geology - Petrology), volume I, Brill Archive, page 8:

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

   • 2023 September 16, Wikipedia contributors, “Canaveilles Group”, in English Wikipedia‎^[1], Wikimedia Foundation:

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