BGS Rock Classification Scheme

Microtonalite - A type of microgranitic-rock. In the Rock Classification Scheme, it is the medium-grained equivalent of tonalite. British Geological Survey Research Report RR/99/06, section 5.1.

Code MCTO
Description Microtonalite - A type of microgranitic-rock. In the Rock Classification Scheme, it is the medium-grained equivalent of tonalite. British Geological Survey Research Report RR/99/06, section 5.1.
Qualifiers No qualifiers currently exist.
Definition Medium-grained, av. between 0.25-2mm normal crystalline intrusive rock; quartz 20-60% of QAPF, feldspar >90% plagioclase, +/- mica/amphibole
Linked data http://data.bgs.ac.uk/id/EarthMaterialClass/RockName/MCTO

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.