| Igneous rock | |
 Quartz monzonite bedrock from a USGS drill core at westernCape Cod, Massachusetts |
Quartz monzonite is anintrusive,felsic,igneous rock that has an approximately equal proportion oforthoclase andplagioclasefeldspars. It is typically a light coloredphaneritic (coarse-grained) toporphyritic granitic rock. The plagioclase is typically intermediate to sodic in composition, andesine to oligoclase.Quartz is present in significant amounts.Biotite and/orhornblende constitute the dark minerals. Because of its coloring, it is often confused withgranite, but whereas granite contains more than 20% quartz, quartz monzonite is only 5–20% quartz. Rock with less than five percent quartz is classified asmonzonite. A rock with more alkali feldspar is asyenite whereas one with more plagioclase is aquartz diorite.[1] The fine grainedvolcanic rock equivalent of quartz monzonite isquartz latite.[1]
The termadamellite was originally applied by A. Cathrein in 1890 to orthoclase-bearing tonalite (likely agranodiorite) at Monte Adamello, Italy, in 1890, but later came to refer to quartz monzonite. The term is now deprecated.[2]
Quartz monzoniteporphyry is often associated withcopper mineralization in theporphyry copperore deposits.[3]
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In theWhite Mountains and western highlands ofNew Hampshire, the Kinsman Quartz Monzonite is an extensive formation that underliesKinsman Mountain, parts ofFranconia Notch,Mount Cardigan, andMount Sunapee.[4]
Stone Mountain inGeorgia is a large quartz monzonitemonadnock.[citation needed]
Quartz monzonite extracted from a quarry inLittle Cottonwood Canyon was used to build several buildings inSalt Lake City,Utah, includingthe Church of Jesus Christ of Latter-day Saints'Salt Lake Temple,Church Administration Building, andConference Center, as well as theUtah State Capitol.[citation needed]
The large boulders ofJoshua Tree National Park in southern California are quartz monzonite.[citation needed]
A large pluton in the Atlanta lobe of theIdaho Batholith, nearMcCall,Idaho, is made of quartz monzonite.[5]
TheGuilford Quartz Monzonite andWoodstock Quartz Monzonite, probably comagmatic, are located in centralMaryland.[citation needed]
InQueensland, Castle Hill, Mount Stuart and Mount Louisa aroundTownsville represent a large quartz monzonite province.[citation needed]
Media related toQuartz monzonite at Wikimedia Commons