Es wurde gezeigt, das bei der Umsetzung von Natriumphosphat mit Calciumnitrat bei Gegenwart von uberschussigem Ammoniak in wasriger Losung als primare Kristallart stets nur Hytlroxylapatit Ca10(PO4)6(OH)2 ausfallt und nicht Tricalciumphosphat, wie bisher angenommen wurde. Fur das weitere Verhalten des Niederschlags beim Trocknen und fur seine Gesamtzusammensetzung ist ausschlaggebend, ob bei der Fallung Gelegenheit gegeben war, uberschussiges P2,05 zu adsorbieren. Wenn das der Fall ist, so werden Zusammensetzungen erreicht, die der des Tricalciumpliosphats naheliegen. Diese Verbindung selbst, wird erst erhalten, wenn die Adsorptionsbindung durch Gluhen zerstort wird. Dabei entstehen darin entsprechend der Gesamtzusammensetzung durch Reaktion im festen Zustand Gemenge von β-Tricalciumphosphat und Hydroxylapatit, vielfach auch mehr oder weniger reines Tricalciumphosphat.

Citrate-insoluble phosphoric acid in di- and tricalcium phosphates: Some factors affecting its determination

Die Bildung schwer löslicher Calciumphosphate aus wäßriger Lösung und die Beziehungen dieser Phosphate zur Apatitgruppe

Analysis of guano specimens from Wooltana cave, formerly occupied by ghost bats (Macroderma gigas), shows the principal mineral is whitlockite with seven other crystalline phases. These include dittmarite NH4MgPO4 ·H2O, biphosphammite (NH4K)H2PO4, syngenite K2Ca(SO4)2 ·H2O, gorgeyite K2Ca5(SO4)6 ·H2O, brushite CaHPO4 ·2H2O, gypsum CaSO4 ·2H2O and whewellite CaC2O4 ·H2O. The mineralogy of the guano samples was determined by powder X-ray diffraction and field emission SEM and the phase analysis was quantified by Reitveld methods. Dittmarite is a very rare mineral and only reported from a small number of localities. It cannot be formed directly in caves as it is normally crystallised from boiling water. We propose that it is formed by decomposition of struvite, NH4MgPO4 ·6H2O, in the presence of ammonia arising from the fresh bat guano. The minerals dittmarite, struvite and newberyite, MgHPO4 ·3H2O, can transform between themselves in caves and in kidney stones (in vitro) according to the conditions....

Additional excerpts

Minerals of the Wooltana Cave, Flinders Ranges, South Australia

Determination of Primary Calcium Phosphate

Water soluble phosphoric acid in ordinary superphosphate and double (or triple) superphosphate consists of mainly monocalcium phosphate, but it also contains one to several per cent free phosphoric acid. Both free acid and water are the essential components in order to know the change in curing or to estimate the reduction of posphoric acid in manufacture of mixed fertilizer.

Citrate-insoluble phosphoric acid in di- and tricalcium phosphates: Some factors affecting its determination

Citations

Die Bildung schwer löslicher Calciumphosphate aus wäßriger Lösung und die Beziehungen dieser Phosphate zur Apatitgruppe

Minerals of the Wooltana Cave, Flinders Ranges, South Australia

Determination of Primary Calcium Phosphate

Determination of free phosphoric acid in superphosphate

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