Phosphorite

Phosphorite is a marine sedimentary rocks, occurs mostly stratabound with other marine rocks with limestones.

Rock description

Phosphorite consists of a mixture of apatite and organic components. The organic components are often recognizable. Are phosphorites pitched escapes in many cases, a foul smell. If not migrated, they are associated with limestone, greensand or greensand stone.

Phosphorites occur in marine clays as grape-like nodules, crusts and concretions. The Phosphoritkörner form beaded and bulbous surfaces of the mineral component is not visible to the naked eye. There are black, rarely brown rocks.

Mineral constituents

The main constituent of the minerals are carbonate - fluorapatite ( Ca 5 [( F, OH, CO3 ) / ( PO4 ) 3] ), which is for the most part of organic origin, and calcite. Phosphorite occurs frequently in conjunction with green glauconite.

Formation

Phosphorites occur mainly in shallow sea near the outer edge of the shelf, at the aufströmt cool, phosphate- rich sea water. Since the solubility of the phosphate is dependent upon the temperature in cold water and more soluble phosphate, the phosphate is bound by chemical and biological processes.

The quantitatively predominant biological origin of phosphorite occurs in different ways. A large part of phosphorites formed on the accumulation of phosphorus in animal excreta or phytoplankton and installation in rigid parts, such as bones and chitin tanks. Some occurrences are viewed as a metabolic product of sulfur bacteria.

The chemical formation of phosphorites due to the direct precipitation from the sea water back or on the metasomatic installation of phosphate in calcareous sediments. The solution and re-precipitation of phosphate plays an important role in the formation of secondary Phosphoritlagerstätten. An example of the associated, very diverse processes is the formation of phosphorites in high rainfall areas of guano, or the Devonian limestone karstic Phosphoritisierung in the Lahn trough the Rhenish Slate Mountains.

Use

The rock phosphate rock used as the starting material for the production of phosphorus, in particular for the production of fertilizer and in the chemical industry. Known deposits of phosphorite - partly in concretions - can be found on Nauru ( almost exhausted ), Morocco, Florida, Tunisia, Estonia and Algeria.

In Germany there is a Phosphoritknollenhorizont near Leipzig. The extraction of phosphorite was in the area earlier between Wetzlar and Katzenelenbogen often, the generation of this Lahnphosphorite mainly took place 1865-1890. This probably Tertiary phosphorites were promoted, for example, from the pit customs house on the territory of the municipality Katzenelenbogen.