. . . "Gabbro - A type of gabbroic-rock. In the Rock Classification Scheme, it is a coarse-grained crystalline igneous rock whose mineral mode plots in field 10 of the quartz - alkali feldspar - plagioclase - feldspathoid (QAPF) diagram. Diorite, gabbro and anorthosite are separated according to the average composition of their plagioclase and the proportion of mafic minerals (M): if M is greater than 10% and An (the anorthite content of plagioclase) is greater than 50% the rock is gabbro. British Geological Survey Research Report RR/99/06, section 5.1 and figs. 9, 11, 12."@en . . . "Gabbro"@en . . . . . . . . . . . . . . . "Gabbro"@en . . . . "stable"@en . . . . . . . . . . . . . . . . . "GB"@en . . . . . . . . . .