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A sedimentary rock composed chiefly of phosphate minerals.



(also phosphate rock), a sedimentary rock composed of more than 50 percent amorphous or microcrystalline minerals of the apatite group (or, on conversion to P2O5, more than 18 percent). In geological prospecting, rocks with satisfactory dressability consisting of 5 to 18 percent P2O5 are also considered phosphorites, especially in open-pit mining.

According to G. I. Bushinskii (1965), there are five types of apatites among the phosphates that compose phosphorites: fluorapatite, carbonate apatite, hydroxylapatite, francolite, and kurskite. According to A. V. Kazakov (1937), the phosphate matter of all phosphorites consists of highly dispersed fluorapatite, and the differences in chemical composition are explained by the presence of mineral impurities. Phosphorites always contain organic matter, carbonates of calcium, magnesium, and iron, clay minerals, pyrite, iron hydroxides, quartz, and chalcedony. They also often contain concentrations of uranium and lanthanides of the cerium group, as well as yttrium, lead, and strontium. Less frequently, they contain impurities of vanadium, scandium, zirconium, selenium, and beryllium. Distinctions are made between massive, nodular (concretional), granular, porous, scoriaceous, pebble, and conglomerate phosphorites on the basis of texture. On the basis of structure, a distinction is made between laminar and sinter phosphorites. Phosphorites are generally black or gray; sometimes they are white, green, red, or yellow.

On the basis of morphological and petrographic characteristics, a distinction is made between deposits of bedded (microgranular), granular, and nodular phosphorites, accumulations of phosphate shells and the skeletons of fish and other organisms, osseous breccia, guano phosphates (formed by the decomposition of the excrement of sea birds), phosphorite pebbles, and phosphatized limestones, marls, and chalk.

Bedded (geosyncline) phosphorites comprise dense uniform rocks with a conchoidal fracture. Composed of round phosphate granules and oolites cemented with phosphate, carbonate, or siliceous matter, they are found in large strata (more than 10 m thick) and are characterized by resistance to destruction and high quality (28–36 percent P2O5). Such deposits occur in the Cambrian formations at Karatau in the USSR, Khubsugul in the Mongolian People’s Republic, K’unyang in the People’s Republic of China, and the Georgina River in Australia, as well as in the Permian deposits of the Rocky Mountains in the United States.

Granular phosphorites comprise carbonate or terrigenous sedimentary rocks with numerous phosphate concretions and organic residues (phosphatized fragments of fish, reptiles, mollusks, and foraminifers) cemented with carbonate, siliceous, and clay matter. The productive strata are usually 2–3 m thick, although some reach 10 m; the deposits contain 22–30 percent P2O5. Granular phosphorites are found in Cretaceous and Paleogenic formations in the European part of the USSR and in North Africa (Algeria, Tunisia, and Morocco) and in the Miocene strata of the Sechura region in Peru.

A distinction is made between marine and continental accumulations on the basis of formation conditions. The origin of marine phosphorites is controversial. According to some scientists, including A. V. Kazakov, A. S. Sokolov, A. I. Smirnov, G. Mansfield, and V. McKelvey, deep ocean waters rich in dissolved phosphorus as a result of the decomposition of plankton were carried by currents to shoals and lost their carbon dioxide in the photosynthesis zone, leading to the chemical precipitation of P2O5. Rejecting the possibility of the chemogenic formation of phosphorites, other investigators, namely, G. I. Bushinskii and V. N. Kholodov, proposed that phosphorus at a certain moment in geological history entered the oceans in large amounts from the continents, was precipitated by plankton and other organisms near the shores (at the mouths of ancient rivers), and, as a result of diagenetic redistribution in the sediment, formed phosphorite deposits.

Most industrial reserves of phosphorus in the world occur in bedded and granular phosphorites; nodular and karst phosphorites and guano deposits are also important sources of phosphorus. Other types of phosphorites are only of theoretical interest.

Up to 90 percent of the phosphorite production is used for the manufacture of phosphate fertilizers, such as phosphorite meal, superphosphate, dicalcium phosphate dihydrate, basic (or Thomas) slag, and ammonium phosphate. In addition, a number of rare elements are extracted in commercial quantities as a byproduct from phosphorites.


Kazakov, A. V. Khimicheskaia priroda fosfatnogo veshchestva fosforitov i ikh genezis. Leningrad, 1937.
Bushinskii, G. I. “Fosfaty kal’tsiia fosforitov.” In Voprosy geologii agronomicheskikh rud. Moscow, 1956.
Bushinskii, G. I. Drevnie fosfority Azii i ikh genezis. Moscow, 1966.
Gimmel’farb, B. M. Zakonomernosti razmeshcheniia mestorozhdenii fosforitov SSSR i ikh geneticheskaia klassifikatsiia. Moscow, 1965.
Shatskii, N. S. “Fosforitonosnye formatsii i klassifikatsiia fosforitovykh zalezhei.” In Doklady Soveshchaniia po osadochnym porodam, fasc. 2. Moscow, 1955.
Kholodov, V. N. O redkikh i radioaktivnykh elementakh v fosforitakh. Moscow, 1963. (Tr. In-ta mineralogii, geokhimii i kristallokhimii redkikh elementov, fasc. 17.)
Mansfield, G. R. “Origin of the Western Phosphates of the United States.” American Journal of Science, 1918, vol. 46, no. 274.


References in periodicals archive ?
The authors therefore conclude that the formation of the earliest worldwide phosphorites 2 billion years ago can be linked to the establishment of sulfur bacteria habitats, triggered by the oxygenation of the Earth.
Between Narva and the Pakri Islands, in the klint and in the valleys cutting into the bedrock, graptolite argillite and phosphorite rich in U are exposed or spread beneath the Quaternary cover.
sedimentary Namibian phosphorites with the rock phosphate material it was
Powdered soil or Nauru phosphorite (5-10mg) was placed in a cylindrical mould (~20mm diameter) and vacuum infiltrated/dispersed in ~2 mL of a low viscosity, low volatility epoxy resin (Epo-thin[R], Buehler Pty Ltd, USA).
Their surroundings were partly destroyed by the phosphorite mining (Fig.
The memorandum written on July 11 by Weizsacker declares that German economical interests in the Balticum are substantial: food products, oil-shale and phosphorite imports are crucial for German war economy, and one should save what can be saved.
3+] ions the maximum binding was up to 242 and 249 mmol per 100 g apatite for magnesium containing synthetic apatites and the triboactivated natural phosphorite sample, respectively.
The vast amount of detailed information on the GA lithology and geochemistry was collected during the prospecting of Estonia's phosphorite resources [15].
The facility produces about 25% of all apatite concentrate recovered in Russia, and almost 100% of this volume is used by EuroChem's own subsidiaries: Phosphorite and Minudobreniya Belorechensk (EuroChem-BMU).
In this period of open struggling for independence, which began in 1987 with a campaign against the use of phosphorite mines in Estonia and culminated with the coup d'etat of 1991, the previous institutions of cultural resistance transformed into large, active and victorious social movements.
At the same time, fertilizer production equipments and technological level have been improved, coal-water slurry gasification technology, powdered coal pressure gasification technology, large sulfur-based compound fertilizer technology and beneficiation technology of mid-low grade phosphorite started to be used widely and have achieved good benefit.