Editing Phosphorite (section)

===Types of phosphorite deposition===

*Phosphate nodules: These are spherical concentrations that are randomly distributed along the floor of continental shelves. Most phosphorite grains are sand size although particles greater than 2&nbsp;mm may be present. These larger grains, referred to as [[Nodule (geology)|nodules]], can range up to several tens of centimeters in size. Phosphate nodules are known to occur in significant quantities offshore northern [[Chile]].<ref>{{Cite journal|title=Potential mineral resources of the Chilean offshore: an overview|journal=[[Andean Geology]]|url=http://www.andeangeology.cl/index.php/revista1/article/view/V47n1-3260/html|last1=García|first1=Marcelo|volume=47|pages=1–13|last2=Correa|first2=Jorge|issue=1|year=2020|last3=Maksaev|first3=Víctor|last4=Townley|first4=Brian|doi=10.5027/andgeoV47n1-3260|doi-access=free}}</ref> 
[[File:Estonian shelly phosphorites.jpg|thumb|right|Shelly phosphorite from Estonia]]
*Bioclastic phosphates or bone beds: Bone beds are bedded phosphate deposits that contain concentrations of small skeletal particles and coprolites.<ref name="Prothero"/> Some also contain invertebrate fossils like brachiopods and become more enriched in P<sub>2</sub>O<sub>5</sub> after diagenetic processes have occurred. Bioclastic phosphates can also be cemented by phosphate minerals.<ref name="Baturin"/> 
*Phosphatization: Phosphatization is a type of rare diagenetic processes. It occurs when fluids that are rich in phosphate are leached from guano.<ref name="Prothero"/> These are then concentrated and reprecipitated in limestone. Phosphatized fossils or fragments of original phosphatic shells are important components within some these deposits.

====Tectonic and oceanographic settings of marine phosphorites====

*Epeiric sea phosphorites: [[Epeiric sea]] phosphorites are within marine shelf environments. These are in a broad and shallow cratonic setting. This is where granular phosphorites, phosphorite hardgrounds, and nodules occur.<ref name="Middleton">Middleton V. Gerald, 2003 Encyclopedia of Earth Sciences series. Encyclopedia of Sediment and Sedimentary Rocks. Kluwer Academic Publishers. Dordrect, Boston, London. pp 131, 727, 519–524.</ref>
*Continental margin phosphorites: Convergent, passive, upwelling, non-upwelling. This environment accumulates phosphorites in the form of hardgrounds, nodules and granular beds.<ref name="D.R Pevear"/> These accumulate by carbonate fluorapatite precipitation during early diagenesis in the upper few tens of centimeters of sediment. There are two different environmental conditions in which phosphorites are produced within continental margins. Continental margins can consist of organic rich sedimentation, strong coastal upwelling, and pronounced low oxygen zones. They can also form in conditions such as oxygen rich bottom waters and organic poor sediments.<ref name="Middleton"/>
*Seamount phosphorites: These are phosphorites that occur in seamounts, guyots, or flat topped seamounts, seamount ridges. These phosphorites are produced in association with iron and magnesium bearing crusts. In this setting the productivity of phosphorus is recycled within an iron oxidation reduction phosphorus cycle. This cycle can also form glauconite which is normally associated with modern and ancient phosphorites.<ref name="Middleton"/>
*Insular phosphorites: Insular phosphorites are located in carbonate islands, plateaus, coral island consisting of a reef surrounding a lagoon or, atoll lagoon, marine lakes. The phosphorite here originates from guano. Replacement of deep sea sediments precipitates, that has been formed in place on the ocean floor.<ref name="Middleton"/>