Phosphorite

Phosphorite, phosphate rock or rock phosphate is a non-<a href="/facts/Detrital/UBsjHYRH">detrital</a> <a href="/facts/Sedimentary_rock/HQDCjrco">sedimentary rock</a> that contains high amounts of <a href="/facts/Phosphate_minerals/WQylquz4">phosphate minerals</a>. The phosphate content of phosphorite (or grade of phosphate rock) varies greatly, from 4% to 20% <a href="/facts/Phosphorus_pentoxide/GKTSUNqS">phosphorus pentoxide</a> (P2O5). Marketed phosphate rock is enriched ("beneficiated") to at least 28%, often more than 30% P2O5. This occurs through washing, screening, de-liming, magnetic separation or flotation. By comparison, the average phosphorus content of sedimentary rocks is less than 0.2%. 
The phosphate is present as <a href="/facts/Fluorapatite/T41AaVmK">fluorapatite</a> Ca5(PO4)3F typically in <a href="/facts/Cryptocrystalline/4vlIFIzv">cryptocrystalline</a> masses (grain sizes < 1 μm) referred to as <a href="/facts/Collophane/f5tYvl1n">collophane</a>-sedimentary apatite deposits of uncertain origin. It is also present as <a href="/facts/Hydroxyapatite/SqcXuXVQ">hydroxyapatite</a> Ca5(PO4)3OH or Ca10(PO4)6(OH)2, which is often dissolved from vertebrate bones and teeth, whereas fluorapatite can originate from <a href="/facts/Hydrothermal_vein/TyETstxF">hydrothermal veins</a>. Other sources also include chemically dissolved phosphate minerals from <a href="/facts/Igneous/xeMJhUah">igneous</a> and <a href="/facts/Metamorphic_rock/JRp6dsCm">metamorphic rocks</a>. Phosphorite deposits often occur in extensive layers, which cumulatively cover tens of thousands of square kilometres of the <a href="/facts/Crust_(geology)/FYG1kP4F">Earth's crust</a>.
<a href="/facts/Limestone/8ntvtFnR">Limestones</a> and <a href="/facts/Mudstone/KWLvUash">mudstones</a> are common phosphate-bearing rocks. Phosphate-rich sedimentary rocks can occur in dark brown to black beds, ranging from centimeter-sized laminae to beds that are several meters thick. Although these thick beds can exist, they are rarely only composed of phosphatic sedimentary rocks. Phosphatic sedimentary rocks are commonly accompanied by or interbedded with <a href="/facts/Shale/bsIhqY5F">shales</a>, <a href="/facts/Chert/pmvbVy6U">cherts</a>, limestone, <a href="/facts/Dolomite_(rock)/EGXDL0zm">dolomites</a> and sometimes <a href="/facts/Sandstone/RP8B6fqL">sandstone</a>. These layers contain the same textures and structures as fine-grained limestones and may represent <a href="/facts/Diagenesis/F1nATwdp">diagenetic</a> replacements of <a href="/facts/Carbonate_minerals/8DUmuAhp">carbonate minerals</a> by phosphates. They also can be composed of peloids, ooids, fossils, and clasts that are made up of apatite. There are some phosphorites that are very small and have no distinctive granular textures. This means that their textures are similar to that of collophane, or fine <a href="/facts/Micrite/GHdnDblt">micrite</a>-like texture. Phosphatic grains may be accompanied by <a href="/facts/Organic_matter/t17tVCvk">organic matter</a>, <a href="/facts/Clay_mineral/A1Sod7Hp">clay minerals</a>, <a href="/facts/Silt/HAxJkhDP">silt</a>-sized detrital grains, and <a href="/facts/Pyrite/41CYREyr">pyrite</a>. Peloidal or pelletal phosphorites occur normally; whereas <a href="/facts/Oolite/2GNzb4AJ">oolitic</a> phosphorites are not common.
Phosphorites are known from <a href="/facts/Proterozoic/sSGXxqUU">Proterozoic</a> <a href="/facts/Banded_iron_formation/b1eA2yAk">banded iron formations</a> in <a href="/facts/Australia/qLHpbppq">Australia</a>, but are more common from <a href="/facts/Paleozoic/5qe2wz7U">Paleozoic</a> and <a href="/facts/Cenozoic/yFslcz6n">Cenozoic</a> sediments. The <a href="/facts/Permian/CYgLgu5u">Permian</a> <a href="/facts/Phosphoria_Formation/6n5kXaXT">Phosphoria Formation</a> of the western <a href="/facts/United_States/P0sCdLe5">United States</a> represents some 15 million years of sedimentation. It reaches a thickness of 420 metres and covers an area of 350,000 km2. Commercially mined phosphorites occur in <a href="/facts/France/CxIeIKM3">France</a>, <a href="/facts/Belgium/YKuMXP5j">Belgium</a>, <a href="/facts/Spain/bIyrB8EY">Spain</a>, <a href="/facts/Morocco/6ly8170M">Morocco</a>, <a href="/facts/Tunisia/4uC8Po6k">Tunisia</a>, <a href="/facts/Saudi_Arabia/uyUpe1J2">Saudi Arabia</a> and <a href="/facts/Algeria/UXDF4Tj6">Algeria</a>. In the United States phosphorites have been mined in <a href="/facts/Florida/cF245A3Q">Florida</a>, <a href="/facts/Tennessee/A3mLY9bu">Tennessee</a>, <a href="/facts/Wyoming/kuKmWryL">Wyoming</a>, <a href="/facts/Utah/te7zUyBX">Utah</a>, <a href="/facts/Idaho/68ELs9Um">Idaho</a> and <a href="/facts/Kansas/koenIXmE">Kansas</a>.

Phosphorite open-in-new

Phosphorite