Wiktionary
n. (context geology English) An intrusive igneous rock composed mostly of plagioclase and orthoclase
Wikipedia
Monzonite is an igneous intrusive rock. It is composed of approximately equal amounts of plagioclase and alkali feldspar, with less than 5% quartz by weight. It may contain minor amounts of hornblende, biotite and other minerals. If quartz constitutes greater than 5%, the rock is termed a quartz monzonite.
If the rock has a greater percentage of alkali feldspar, it grades into a syenite. With an increase in calcic plagioclase and mafic minerals the rock type becomes a diorite. The volcanic equivalent is the latite.
Usage examples of "monzonite".
Her world was four and a half billion years old, and she had a vocabulary newly full of strike-slip faults, cactoliths, andesite, and monzonite, and she made tilting slipping shapes with her hands to show us how the mountains came about.