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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.[1] It may contain minor amounts of hornblende, biotite and other minerals. If quartz constitutes greater than 5%, the rock is termed a quartz monzonite.[2]

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.[2]


Monzonite was originally named after the Monzoni district in Spain where it is abundant. As rock definitions have been systematized and codified, this association has lost any relevance to the rock's definition.[1]

See alsoEdit


  1. 1.0 1.1 Le Maitre, R.W., Igneous Rocks: A Classification and Glossary of Terms Cambridge University Press, 2nd ed, pp. 113 ISBM 0-521-66215
  2. 2.0 2.1 Klein, Cornelis and Cornelius S. Hurlbut, Jr., Manual of Mineralogy, Wiley, 20th ed, pp. 480-484 ISBN 0-471-80580-7