BGS Rock Classification Scheme

Gneiss, hornblende-biotite

Code	GNEHB
Description	Gneiss, hornblende-biotite
Qualifiers	hornblende   biotite
Definition	Med-coarse-grained (av. 0.25-16mm) crystalloblastic metamorphic rock (protolith undefined),>5mm irregular/discontinuous layers defined by contrasting text/grainsize/mineralogy, well developed preferred min orientation common. Biotite>hornblende both 5-20%
Linked data	http://data.bgs.ac.uk/id/EarthMaterialClass/RockName/GNEHB

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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.