Editing Shocked quartz (section)

==Formation==
[[File:820qtz.jpg|thumb|right|Photomicrograph of a shocked quartz grain (0.13&nbsp;mm across) from the [[Chesapeake Bay impact crater]], showing shock lamellae]]
Shocked quartz is usually associated in nature with two high-pressure [[polymorphism (materials science)|polymorphs]] of [[silicon dioxide]]: [[coesite]] and [[stishovite]]. These polymorphs have a crystal structure different from standard quartz. This structure can be formed only by intense pressure (more than 2 [[Pascal (unit)|gigapascals]]), but at moderate temperatures. Coesite and stishovite are usually viewed as indicative of [[impact event]]s or [[eclogite facies]] metamorphism (or [[nuclear explosion]]), but are also found in sediments prone to [[lightning]] strikes and in [[fulgurite]]s.<ref>{{cite journal |last=Melosh |first=H.J. |title=Impact geologists, beware! |journal=Geophysical Research Letters |volume=44 |issue=17 |pages=8873–8874 |doi=10.1002/2017GL074840 |year=2017 |bibcode=2017GeoRL..44.8873M |s2cid=134575031 }}</ref><ref name="ammin.geoscienceworld.org"/>