BGS Rock Classification Scheme

Quartz-monzogabbro - A type of gabbroic-rock. In the Rock Classification Scheme, it is a coarse-grained crystalline igneous rock whose mineral mode plots in field 9* of the quartz - alkali feldspar - plagioclase - feldspathoid (QAPF) diagram. Quartz-monzodiorite and quartz-monzogabbro are separated according to the average composition of their plagioclase: if An (the anorthite content of plagioclase) is greater than 50% the rock is quartz-monzogabbro. British Geological Survey Research Report RR/99/06, section 5.1 and figs. 9, 11, 12.

Code QMZGB
Description Quartz-monzogabbro - A type of gabbroic-rock. In the Rock Classification Scheme, it is a coarse-grained crystalline igneous rock whose mineral mode plots in field 9* of the quartz - alkali feldspar - plagioclase - feldspathoid (QAPF) diagram. Quartz-monzodiorite and quartz-monzogabbro are separated according to the average composition of their plagioclase: if An (the anorthite content of plagioclase) is greater than 50% the rock is quartz-monzogabbro. British Geological Survey Research Report RR/99/06, section 5.1 and figs. 9, 11, 12.
Qualifiers No qualifiers currently exist.
Definition Coarse-grained, av. between 2-16mm normal crystalline intrusive rock; quartz 5-20% of QAPF, feldspar 65-90% plagioclase (>50% An), +/-mica/pyroxene/amphibole/olivine
Linked data http://data.bgs.ac.uk/id/EarthMaterialClass/RockName/QMZGB

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.