Editing Quartz (section)

== Early studies ==

Roman naturalist [[Pliny the Elder]] believed quartz to be water [[ice]], permanently frozen after great lengths of time.<ref>Pliny the Elder, ''The Natural History'', Book 37, Chapter 9.  Available on-line at:  [https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.02.0137%3Abook%3D37%3Achapter%3D9 Perseus.Tufts.edu] {{Webarchive|url=https://web.archive.org/web/20121109044605/http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.02.0137%3Abook%3D37%3Achapter%3D9 |date=9 November 2012 }}.</ref> He supported this idea by saying that quartz is found near glaciers in the Alps, but not on volcanic mountains, and that large quartz crystals were fashioned into spheres to cool the hands. This idea persisted until at least the 17th century. He also knew of the ability of quartz to split light into a [[spectrum]].<ref>{{cite journal |last1=Tutton |first1=A.E. |year=1910 |title=Rock crystal: its structure and uses |journal=RSA Journal |volume=59 |page=1091 |jstor=41339844}}</ref>

In the 17th century, [[Nicolas Steno]]'s study of quartz paved the way for modern [[crystallography]]. He discovered that regardless of a quartz crystal's size or shape, its long prism faces always joined at a perfect 60° angle, thus discovering the [[law of constancy of interfacial angles]].<ref>Nicolaus Steno (Latinized name of Niels Steensen) with John Garrett Winter, trans., ''The Prodromus of Nicolaus Steno's Dissertation Concerning a Solid Body Enclosed by Process of Nature Within a Solid'' (New York, New York:  Macmillan Co., 1916). On [https://books.google.com/books?id=5IYNAAAAYAAJ&pg=PA272 page 272] {{Webarchive|url=https://web.archive.org/web/20150904013105/https://books.google.com/books?id=5IYNAAAAYAAJ&pg=PA272 |date=4 September 2015 }}, Steno states his law of constancy of interfacial angles:  "Figures 5 and 6 belong to the class of those which I could present in countless numbers to prove that in the plane of the axis both the number and the length of the sides are changed in various ways without changing the angles; … "</ref>