Editing Quartz (section)

== Occurrence ==
[[File:Quartz vein in sandstone (Thunderhead Sandstone, Neoproterozoic; Clingmans Dome, Great Smoky Mountains, North Carolina, USA) 2 (36619574200).jpg|thumb|Quartz vein in sandstone, North Carolina]]
Quartz is a defining constituent of [[granite]] and other [[felsic]] [[igneous rock]]s. It is very common in [[sedimentary rock]]s such as [[sandstone]] and [[shale]]. It is a common constituent of [[schist]], [[gneiss]], [[quartzite]] and other [[metamorphic rock]]s.{{sfn|Hurlbut|Klein|1985}} Quartz has the lowest potential for [[weathering]] in the [[Goldich dissolution series]] and consequently it is very common as a residual mineral in stream sediments and residual [[soil]]s. Generally a high presence of quartz suggests a "[[Maturity (sedimentology)|mature]]" rock, since it indicates the rock has been heavily reworked and quartz was the primary mineral that endured heavy weathering.<ref>{{cite book |last1=Boggs |first1=Sam |title=Principles of sedimentology and stratigraphy |date=2006 |publisher=Pearson Prentice Hall |location=Upper Saddle River, N.J. |isbn=0131547283 |edition=4th |page=130}}</ref>

While the majority of quartz crystallizes from molten [[magma]], quartz also chemically precipitates from hot [[Hydrothermal circulation|hydrothermal]] [[Vein (geology)|veins]] as [[gangue]], sometimes with [[ore]] minerals like gold, silver and copper. Large crystals of quartz are found in magmatic [[pegmatite]]s.{{sfn|Hurlbut|Klein|1985}} Well-formed crystals may reach several meters in length and [[mass|weigh]] hundreds of kilograms.<ref>{{cite journal|first1=Richard H. |last1=Jahns |title=The genesis of pegmatites: I. Occurrence and origin of giant crystals |journal=American Mineralogist |year=1953 |volume=38 |number=7–8 |pages=563–598 |url=https://pubs.geoscienceworld.org/msa/ammin/article-abstract/38/7-8/563/539244 |access-date=7 April 2021}}</ref>

The largest documented single crystal of quartz was found near [[Itaporã|Itapore]], [[Goyaz|Goiaz]], Brazil; it measured approximately {{convert|6.1|x|1.5|x|1.5|m|ft|0|abbr=on}} and weighed over {{cvt|88000|lb|kg|order=flip|sigfig=3}}.<ref>{{cite journal| url = http://www.minsocam.org/ammin/AM66/AM66_885.pdf| journal = American Mineralogist| volume = 66| pages = 885–907 (903)| year = 1981| title = The largest crystals| author = Rickwood, P. C.| access-date = 7 March 2013| archive-url = https://web.archive.org/web/20130825210420/http://www.minsocam.org/ammin/AM66/AM66_885.pdf| archive-date = 25 August 2013| url-status = live| df = dmy-all}}</ref>