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A phaneritic (visibly crystalline) plutonic rock composed chiefly of sodic plagioclase and alkali feldspar, with subordinate amounts of dark-colored minerals, intermediate between syenite and dorite.



(named after the city of Monzoni, Italy, in the Tirol), crystalline igneous rock consisting of approximately equal amounts of common potash feldspar and lime-soda feldspar (orthoclase and labradorite) and of a ferromagnesian mineral, usually pyroxene. In more acid varieties of monzonite a small amount of quartz may also be present; in more basic kinds there may be olivine. Chemically the group of monzonite rocks occupies an intermediate position between gabbros and syenites (average silica content of 55–65 percent); therefore monzonites are also called gabbro-syenites. Monzonite is a dense large-grained rock that is attractive when polished. It is used as a building material. Monzonites occur in many regions of the USSR—for example, the Ukraine and the Baikal region; abroad they are found in Italy, Norway, and other countries.

References in periodicals archive ?
Granosyenitic, syenitic, and quartz monzonitic rocks (mangeritic rocks after Bogatikov & Birkis, 1973) and associated gabbro-anorthosites and ultramafic rocks are found in the southern part of the batholith (Fig.
The quartz monzonitic rocks in the southern part of the Riga batholith are brownish, mostly coarse-grained porphyritic rocks containing megacrysts of euhedral, mesoperthitic alkali feldspar.
Identification of Paleoproterozoic anorthositic and monzonitic rocks in the vicinity of the Mesoproterozoic Nain Plutonic Suite, Labrador; U-Pb evidence.
The sulphides have occurred as both infill and alteration (spots) and also overprint the monzonitic host sill/dyke rock.
Mineralization is hosted in an altered, brecciated and fractured, felsic intrusive, of monzonitic to monzodioritic composition, which carries extensive hematite, chlorite, and carbonate.
The Mitchell Zone is an area of intensely stockworked and veined, mainly phyllic altered, variably foliated volcanics and monzonitic porphyry exposed over an area of at least 200 by 1,000 meters.
Bald Butte represents a stockwork molybdenite system that is spatially and genetically related to the emplacement of a multi-phase Eocene age composite stock of granitic to quartz monzonitic composition.
At the Main Copper Zone, mineralization is associated with potassic altered monzonitic porphyries which intrude quartz-chlorite-magnetite altered volcanics.
Tertiary monzonitic intrusions host a number of mineralized veins mined in the district, and are probably the source of the mineralized veins and structures.
There is evidence of several old gold and polymetallic prospects at Guerrero, some of which occur in close proximity to the large Tertiary monzonitic intrusive which appears within the volcanic and volcano-sedimentary units in the southwest corner of the concession.
The Nordik Southeast is a magnetic/chargeability high coincident with potassic altered monzonitic to dioritic intrusive and volcanic rocks.