Editing Flint (section)

==Origin==
[[File:Silica pseudomorph after halite crystals and silicified remains of algae 6.jpg|thumb|Silicified remains of algae and silica pseudomorph after halite in flint. Pebble of Loire near Marcigny, France. Image width: about 5 mm.]]

The exact mode of formation of flint is not yet clear, but it is thought that it occurs as a result of chemical changes in compressed sedimentary rock formations during the process of [[diagenesis]]. One [[hypothesis]] is that a gelatinous material fills cavities in the sediment, such as holes bored by [[crustaceans]] or [[molluscs]] and that this becomes [[silicification|silicified]]. This hypothesis would certainly explain the complex shapes of flint nodules that are found. The source of dissolved silica in the porous media could be the [[spicules of silicious sponges]] ([[demosponge]]s).<ref name=Flints/> Certain types of flint, such as that from the south coast of England and its counterpart on the French side of the [[English Channel|Channel]], contain trapped fossilised marine flora. Pieces of coral and vegetation have been found preserved inside the flint similar to insects and plant parts within [[amber]]. Thin slices of the stone often reveal this effect.

[[File:flintbeach.jpg|thumb|upright|Pebble beach made up of flint nodules eroded from the nearby [[chalk]] cliffs, [[Cape Arkona]], [[Rügen]], northeast Germany]]
Flint sometimes occurs in large [[flint fields]] in [[Jurassic]] or [[Cretaceous]] beds, for example, in Europe. Puzzling giant flint formations known as [[paramoudra]] and flint circles are found around Europe but especially in Norfolk, England, on the beaches at [[Beeston Regis#Beeston Hill (Beeston Bump)|Beeston Bump]] and [[West Runton]].<ref>[http://www.museums.norfolk.gov.uk/default.asp?Document=400.500.100.030x2 Museums.norfolk.gov.uk] {{webarchive |url=https://web.archive.org/web/20071012025938/http://www.museums.norfolk.gov.uk/default.asp?Document=400.500.100.030x2 |date=12 October 2007 }}</ref>

The "Ohio flint" is the official gemstone of Ohio state. It is formed from limey debris that was deposited at the bottom of inland [[Paleozoic]] seas hundreds of millions of years ago that hardened into [[limestone]] and later became infused with [[silica]]. The flint from Flint Ridge is found in many hues like red, green, pink, blue, white, and grey, with the colour variations caused by minute impurities of iron compounds.<ref>{{cite book |last1=McPherson |first1=Alan |title=State Geosymbols: Geological Symbols of the 50 United States |year=2011 |publisher=AuthorHouse |isbn=9781463442644 |url=https://books.google.com/books?id=T1Q8fpGYzPMC&pg=PA113 |access-date=28 March 2019 |archive-date=1 August 2020 |archive-url=https://web.archive.org/web/20200801190038/https://books.google.com/books?id=T1Q8fpGYzPMC&pg=PA113 |url-status=live }}</ref>

Flint can be coloured: sandy brown, medium to dark grey, black, reddish brown or an off-white grey.<ref>http://prospectingnb.blogspot.com/2010_06_01_archive.html{{Dead link|date=January 2022 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>