Assessment of the molecular structure of natrodufrenite - NaFe2+Fe53+ (PO4)(4)(OH)(6) center dot 2(H2O), a secondary pegmatite phosphate mineral from Minas Gerais, Brazil

作者：Lopez Andres; Frost Ray L^*; Xi Yunfei; Scholz Ricardo; Belotti Fernanda Maria; Ribeiro Erika

来源：Journal of Molecular Structure, 2013, 1051: 265-270.

DOI：10.1016/j.molstruc.2013.08.018

• Natrodufrenite
• Phosphate
• Pegmatite
• Infrared spectroscopy
• Raman spectroscopy

The mineral natrodufrenite a secondary pegmatite phosphate mineral from Minas Gerais, Brazil, has been studied by a combination of scanning electron microscopy and vibrational spectroscopic techniques. Electron probe analysis shows the formula of the studied mineral as (Na0.88Ca0.12)(Sigma 1.00)(Fe0.722+Mn0.11Mg0.08Ca0.04Zr0.01Cu0.01)(Sigma 0.97)(Fe4893+Al0.02)(Sigma 4.91)(PO4)(3.96)(OH6.15F0.07)(6.22) center dot 2.05(H2O). Raman spectroscopy identifies an intense peak at 1003 cm(-1) assigned to the PO43- v(1) symmetric stretching mode. Raman bands are observed at 1059 and 1118 cm(-1) and are attributed to the PO43- v(3) antisymmetric stretching vibrations. A comparison is made with the spectral data of other hydrate hydroxy phosphate minerals including cyrilovite and wardite. Raman bands at 560, 582,619 and 668 cm(-1) are assigned to the v(4) PO43- bending modes and Raman bands at 425,444, 477 and 507 cm(-1) are due to the v(2) PO43- bending modes. Raman bands in the 2600-3800 cm(-1) spectral range are attributed to water and OH stretching vibrations. Vibrational spectroscopy enables aspects of the molecular structure of natrodufrenite to be assessed.

• 出版日期2013-11-5