quartz diorite

{{Short description|Igneous, plutonic rock}}

File:Mineraly.sk - kremdiorit.jpgs, Slovakia]]

Quartz diorite is an igneous, plutonic (intrusive) rock, of felsic composition, with phaneritic texture. Feldspar is present as plagioclase (typically oligoclase or andesine) with 10% or less potassium feldspar. Quartz is present at between 5 and 20% of the rock. Biotite, amphiboles and pyroxenes are common dark accessory minerals.{{Cite book|title=Petrography; an introduction to the study of rocks in thin sections, by Howel Williams, Francis J. Turner, and Charles M. Gilbert.|last1=Williams|first1=Howel|last2=Turner|first2=Francis J|last3=Gilbert|first3=Charles M|date=1954|publisher=W.H. Freeman|location=San Francisco|language=English|oclc=976619418}}

Quartz diorite occurs in association with other granitic rock such as granodiorite, and with volcanic rock. In western North America a "quartz diorite line" occurs; west of this line, the dominant granitic rock is quartz diorite.{{cite journal | url=https://www.jstor.org/stable/30063866 | jstor=30063866 | last1=Moore | first1=James G. | title=The Quartz Diorite Boundary Line in the Western United States | journal=The Journal of Geology | date=1959 | volume=67 | issue=2 | pages=198–210 | doi=10.1086/626573 | bibcode=1959JG.....67..198M | url-access=subscription }}