A vibrational spectroscopic study of the phosphate mineral zanazziite - Ca2(MgFe2+)(MgFe2+Al)4Be4(PO4)6⋅6(H2O)

Frost, Ray L., Xi, Yunfei, Scholz, Ricardo, Belotti, Fernanda M., & Dias Menezes Filho, Luiz Alberto (2013) A vibrational spectroscopic study of the phosphate mineral zanazziite - Ca2(MgFe2+)(MgFe2+Al)4Be4(PO4)6⋅6(H2O). Spectrochimica Acta Part A : Molecular and Biomolecular Spectroscopy, 104, pp. 250-256.

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Zanazziite is the magnesium member of a complex beryllium calcium phosphate mineral group named roscherite. The studied samples were collected from the Ponte do Piauí mine, located in Itinga, Minas Gerais. The mineral was studied by electron microprobe, Raman and infrared spectroscopy. The chemical formula can be expressed as Ca2.00(Mg3.15,Fe0.78,Mn0.16,Zn0.01,Al0.26,Ca0.14)Be4.00(PO4)6.09(OH)4.00⋅5.69(H2O) and shows an intermediate member of the zanazziite–greinfeinstenite series, with predominance of zanazziite member.

The molecular structure of the mineral zanazziite has been determined using a combination of Raman and infrared spectroscopy. A very intense Raman band at 970 cm−1 is assigned to the phosphate symmetric stretching mode whilst the Raman bands at 1007, 1047, 1064 and 1096 cm−1 are attributed to the phosphate antisymmetric stretching mode. The infrared spectrum is broad and the antisymmetric stretching bands are prominent. Raman bands at 559, 568, 589 cm−1 are assigned to the ν4 out of plane bending modes of the PO4 and HPO4 units. The observation of multiple bands supports the concept that the symmetry of the phosphate unit in the zanazziite structure is reduced in symmetry. Raman bands at 3437 and 3447 cm−1 are attributed to the OH stretching vibrations; Raman bands at 3098 and 3256 are attributed to water stretching vibrations. The width and complexity of the infrared spectral profile in contrast to the well resolved Raman spectra, proves that the pegmatitic phosphates are better studied with Raman spectroscopy.

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ID Code: 58689
Item Type: Journal Article
Refereed: Yes
Keywords: Raman spectroscopy, Infrared spectroscopy, Zanazziite, Roscherite group, Greinfeinstenite, Phosphate
DOI: 10.1016/j.saa.2012.11.017
ISSN: 1386-1425
Subjects: Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000) > PHYSICAL CHEMISTRY (INCL. STRUCTURAL) (030600) > Structural Chemistry and Spectroscopy (030606)
Divisions: Current > Schools > School of Chemistry, Physics & Mechanical Engineering
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2012 Elsevier B.V. All rights reserved.
Copyright Statement: This is the author’s version of a work that was accepted for publication in Spectrochimica Acta Part A : Molecular and Biomolecular Spectroscopy. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Spectrochimica Acta Part A : Molecular and Biomolecular Spectroscopy, [VOL 104, ISSUE -, (2013)] DOI: 10.1016/j.saa.2012.11.017
Deposited On: 04 Apr 2013 00:44
Last Modified: 24 Apr 2013 22:24

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