Editing Quartzite (section)

{{Short description|Hard, non-foliated metamorphic rock}}
{{For|the similarly-named town|Quartzsite, Arizona}}{{Infobox rock|name=Quartzite|type=Metamorphic|caption=Quartzite, containing darker bands of phengite and chlorite, from Maurienne Valley in the [[French Alps]]|composition=Quartz|regoliths=|image=Quartzite Sollières.jpg|protolith=Quartz [[Sandstone]]|fabric=Non-foliated}}[[File:Sample of Quartzite.JPG|thumb|Quartzite can have a grainy, glassy, sandpaper-like surface]]

'''Quartzite''' is a hard, non-[[Foliation (geology)|foliated]] [[metamorphic rock]] that was originally pure [[quartz]] [[sandstone]].<ref name= EG>Essentials of Geology, 3rd Edition, Stephen Marshak, p 182</ref><ref name="MII">{{cite web|url=http://www.mii.org/Minerals/photoquartzite.html|title=Quartzite|last=Powell|first=Darryl|publisher=Mineral Information Institute|access-date=2009-09-09|url-status=dead|archive-url=https://web.archive.org/web/20090302072709/http://www.mii.org/Minerals/photoquartzite.html|archive-date=2009-03-02}}</ref> Sandstone is converted into quartzite through heating and pressure usually related to [[tectonics|tectonic]] compression within [[orogeny|orogenic belts]], and hence quartzite is a metasandstone. Pure quartzite is usually white to grey, though quartzites often occur in various shades of pink and red due to varying amounts of [[hematite]]. Other colors, such as yellow, green, blue  and orange, are due to other minerals.

The term ''quartzite'' is also sometimes used for very hard but unmetamorphosed [[sandstones]] that are composed of quartz grains thoroughly cemented with additional quartz. Such sedimentary rock has come to be described as '''orthoquartzite''' to distinguish it from metamorphic quartzite, which is sometimes called '''metaquartzite''' to emphasize its metamorphic origins.<ref name=jackson1997>{{cite book |editor1-last=Jackson |editor1-first=Julia A. |title=Glossary of geology. |date=1997 |publisher=American Geological Institute |location=Alexandria, Virginia |isbn=0922152349 |edition=Fourth |page=525}}</ref><ref name=oxford2013>{{cite book |last1=Allaby |first1=Michael |title=A dictionary of geology and earth sciences |date=2013 |publisher=Oxford University Press |location=Oxford |isbn=9780199653065 |edition=Fourth}}</ref>

Quartzite is very resistant to chemical [[weathering]] and often forms ridges and resistant hilltops. The nearly pure silica content of the rock provides little material for [[soil]]; therefore, the quartzite ridges are often bare or covered only with a very thin layer of soil and little (if any) vegetation. Some quartzites contain just enough weather-susceptible nutrient-bearing minerals such as [[carbonates]] and [[Chlorite group|chlorite]] to form a loamy, fairly fertile though shallow and stony soil.

Quartzite has been used since prehistoric times for stone tools. It is presently used for decorative dimension stone, as crushed stone in highway construction, and as a source of [[silica]] for production of [[silicon]] and silicon compounds.