Phosphate minerals and

Perovskites also exhibit reaction relationships with phosphate minerals and exotic alkali-titanium-silicate minerals under late-stage magmatic conditions. In a systematic study of loparite mineral chemistry in the Lovozero alkaline complex, Russia, Kogarko et al. (2002) have... 

Lapis lazuli is a metamorphic rock composed of three minerals, blue lazu-rite, white calcite, and brassy pyrite. This stone was highly prized by some cultures, both ancient and modern, because of its intense blue color. Most good-quality lapis lazuli has been mined in Afghanistan and southern Russia, although small deposits have been found elsewhere in the world. Common imitations of lapis lazuli are glass, lazulite (a phosphate mineral), and sodalite (a tectosilicate mineral similar to lazurite). 

Figure 17 Speciation of Nd in a number of world rivers calculated in the solution fraction (<0.2 pm) by considering inorganic complexes (carbonate and phosphate), mineral and organic colloidal Nd species (dicarboxylic...

Complex ions are also formed with citrate and anions of other organi acids, thiocyanate and phosphates. The phosphates are important in view c the occurrence of uranium in phosphate minerals, and species such a U02H2PC>4 and U02H3P0 +, and at high concentrations anionic coir plexes are known. 

Readily available phosphorus This form is present in soil pore water and the exchangeable pool. Phosphorus in this pool is continuously replenished from other stable pools at various rates, depending on the solubility of phosphate minerals and the physicochemical properties of soils. Inorganic phosphorus is extracted with neutral salts such as NaCl, KCl, NH4CI, and NaHCOj. 

Table 4.2. Infrared absorption band centers for goethite, phosphated goethites, phosphate minerals, and aqueous phosphate anions ... 

During igneous phosphate rock weathering, a wide variety of secondary phosphate minerals and clays may form. These phosphate minerals and clays indiide all the minerals previously mentioned in conjunction vwth sedimentary deposits. The residuum over such deposits is typically very rich in iron and contains significant proportions of hematite and goethite. 

Schreibesite, (Fe,Ni)3P, and Florenskyite, FeTiP, have been detected in meteorites and in lunar samples [35]. These constitute rare examples of naturally occurring reduced phosphate minerals, and phosphides of this type may be present in the earth s core. 

Acid magmas from the interior of the earth react with basic rocks and start to sohdi-fy. Uranium is enriched in the remaining melts. When these finally solidify, the uranium content may be 100 g/tonne (100 ppm, 0.01%). Compared to the mean content in the earth s crust, 2.7 ppm, this is a considerable geochemical enrichment. In addition, uranium is concentrated into phosphate minerals and coal, especially brown coal. This is the background to the fact that coal-fired power stations emit more uranium than nuclear power stations ... 

Sedimentary marine phosphorites are composed principally of phosphatic minerals, and many contain significant amounts of disseminated uranium. These phosphorites have been classified as either miogeosynclinal or platform types. Four additional types that are low in uranium and of little economic importance are residual phosphorites, phosphatized rock, river pebble deposits and guano. 

Ajo D, Favaro M, Pozza G et al (1997) Near-Infrared photoluminescence in phosphate minerals and related glass-ceramics. J Mater Sci 32 4217-4220 Altschuler Z (1980) The hearing of geochemistry on the recovery of uranium and rare earth in phosphorites. Proc 2nd Intemat Cong Phosphoms Compounds, Boston, p 605-625 Bakhtin A, Gorohets B (1992) Optical spectroscopy of minerals and ores and its use in geology. 

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