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Quartz monzonite or adamellite is an intrusive, felsic, igneous rock that has an approximately equal proportion of orthoclase and plagioclase feldspars. It is typically a light colored phaneritic (coarse-grained) to porphyritic granitic rock. 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.〔(Classification of Igneous Rocks )〕 The fine grained volcanic rock equivalent of quartz monzonite is quartz latite.〔 Quartz monzonite porphyry is often associated with copper mineralization in the porphyry copper ore deposits.〔Titley, Spencer R. and Carol L. Hicks, ''Geology of the Porphyry Copper Deposits,'' University of Arizona Press, 1966, p. 35〕 ==Geographic distribution== A 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. Quartz monzonite extracted from a quarry in Little Cottonwood Canyon was used to build several buildings in Salt Lake City, Utah, 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 large boulders of Joshua Tree National Park in southern California are quartz monzonite. A large pluton in the Atlanta lobe of the Idaho Batholith, near McCall, Idaho, is made of quartz monzonite.〔(Idaho Batholith )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Quartz monzonite」の詳細全文を読む スポンサード リンク
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