BGS Rock Classification Scheme

Gneiss, micaceous

Code GNSMI
Description Gneiss, micaceous
Qualifiers micaceous      
Definition Medium to coarse-grained (av. 0.25-16mm) crystalloblastic metamorphic rock (protolith undefined) with >5mm irregular/discontinuous layers defined by contrasting texture/grainsize/mineralogy,well developed preferred mineral orientation common. 5-20% micas.
Linked data http://data.bgs.ac.uk/id/EarthMaterialClass/RockName/GNSMI

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.