BGS Rock Classification Scheme

Granite, gneissose

Code	GNGNS
Description	Granite, gneissose
Qualifiers	gneissose
Definition	Coarse-grained (av. 2-16mm), normal crystalline, intrusive meta-granite protolith, >5mm irregular/discontinuous layers of contrasting grain size/mineralogy with preferred mineral orientation; qtz 20-60% of QAPF, feld 35-90% alkali feld +/- mica/amphibole
Linked data	http://data.bgs.ac.uk/id/EarthMaterialClass/RockName/GNGNS

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CAVEAT

"Thumbnail" definitions attached to some of the table entries are an interim attempt to provide simple short descriptions of the "unqualified" rock types presented within the BGS Rock Classification Scheme. Every effort has been made to ensure accuracy and consistency but minor contradictions or omissions might be present. The BGS welcomes any feedback pointing out such minor imperfections and/or providing constructive comment and suggestions for improvement of the definitions. In the first instance such feedback should be directed to Dr Tim McCormick.