[′gran·ət ¦nīs]
A banded metamorphic rock derived from igneous or sedimentary rocks mineralogically equivalent to granite.



a holocrystalline shale rock consisting, like granite, of quartz, potash feldspar, acid plagioclase, and mica (predominantly biotite).

A majority of researchers believe granite-gneisses to be granites that have crystallized deep in the earth’s crust either during the cooling of the magmatic melt under directed pressure or during the process of the magma’s movement, as a result of which there is parallel arrangement of the mica (more rarely, of the other minerals). It is extremely difficult to distinguish the magmatic granite-gneisses from the meta-morphic gneisses. For this reason, the name granite-gneiss is sometimes used to denote macrocrystalline gneisses that are rich in granitic material.

References in periodicals archive ?
Geology Type granite-gneiss and retrograde granulite gneiss with minor amounts of granite and granodiorite.
The soils are formed from charnokite and granite-gneiss rocks.
80 m, underlain by hard partially weathered granite-gneiss.
The formation of Ultisols on granite-gneiss under humid tropical weathering conditions appears to be a common occurrence in Indian subcontinent as evidenced in the present study and elsewhere (Bhattacharyya et al.
The Ultisols of Kerala were formed on saprolite of granite-gneiss rock in the tropical humid climate that began at the end of the Cretaceous (Kumar 1986; Tardy etal.
Large-scale advection of granitic melts into the upper crust is thought to have contributed to the crustal-scale amplitude (10-15 km) of composite granite-gneiss domes, many of which are cored by young granites (Bleeker, 2002).
A number of important shears have been recognised along meta-sedimentary / granite-gneiss contacts, as well as inflections on major shears which may be important in localising mineralization.
by Archean basement granite-gneiss of the Congo Craton, and extends from the