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The unit cell and space-group of chlor-spodiosite (Ca2PO4Cl)

Published online by Cambridge University Press:  14 March 2018

A. L. Mackay*
Affiliation:
Birkbeck College Research Laboratory, University of London

Extract

As part of a study of the structure of whitlockite (β-Ca3(PO4)2) attempts were made to prepare single crystals of the mineral synthetically. At 1180° there is a polymorphic transition from the rhombohedral β-form to a high-temperature monoclinie form α-Ca3(PO4)2. The density of the α-form is 12% less than that of the β-form and large crystals were not found to transform without powdering. CaCl2 was therefore added as a flux to see whether crystals of Ca3(PO4)2 could be produced from a melt below 1180°. The melting point of pure Ca3(PO4)2 is about 1800°. In addition to chlorapatite (Ca5(PO4)3C1), a phase of composition Ca2PO4Cl was produced. This compound had been earlier observed by Cameron and McCaughey, who identified the crystals as being closely related to the mineral spodiosite (Ca2PO4F).

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1953

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References

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