- Quartz monzonite
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Quartz monzonite Igneous Rock 
Quartz monzonite bedrock from a UGSG drill core at Western Cape Cod, MassachusettsQuartz monzonite (or adamellite) is an intrusive igneous rock that has an approximately equal proportion of orthoclase and plagioclase feldspars. The plagioclase is typically intermediate to sodic in composition, andesine to oligoclase. Quartz is present in significant amounts. Biotite and/or hornblende constitute the dark minerals. Because of its coloring, it is often confused with granite, but whereas granite contains more than 20% quartz, quartz monzonite is only 5-20% quartz. Rock with less than five percent quartz is classified as monzonite. A rock with more alkali feldspar is a syenite whereas one with more plagioclase is a quartz diorite.[1]
QAPF diagram for plutonic rocks
The fine grained volcanic rock equivalent of quartz monzonite is quartz latite.[1]
Quartz monzonite porphyry is often associated with copper mineralization in the porphyry copper ore deposits.[2]
Geographic distribution
Quarry for the Salt Lake Temple with boulders and detached masses being worked by stone cuttersA massive outcrop of this igneous rock can be seen on the bald summit of Croydon Mountain near Cornish, New Hampshire. Stone Mountain in Georgia is a large quartz monzonite monadnock.
It is also the material used to construct several buildings in Salt Lake City, including the LDS Church's Salt Lake Temple, the Utah State Capitol, the LDS Church Administration Building, and the facade of the nearby LDS Conference Center. The blocks used were quarried in nearby Little Cottonwood Canyon.
References
- ^ a b Classification of Igneous Rocks
- ^ Titley, Spencer R. and Carol L. Hicks, Geology of the Porphyry Copper Deposits, University of Arizona Press, 1966, p. 35
External links
Media related to Quartz monzonite at Wikimedia Commons
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