Quartz diorite

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.^[1]

Quartz diorite from Dúbrava, Nízke Tatry Mountains, Slovakia

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.^[2]

References

1. Williams, Howel; Turner, Francis J; Gilbert, Charles M (1954). Petrography; an introduction to the study of rocks in thin sections, by Howel Williams, Francis J. Turner, and Charles M. Gilbert. San Francisco: W.H. Freeman. OCLC 976619418.
2. Moore, James G. (1959). "The Quartz Diorite Boundary Line in the Western United States". The Journal of Geology. 67 (2): 198–210. Bibcode:1959JG.....67..198M. doi:10.1086/626573. JSTOR 30063866.

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