A vibrational spectroscopic study of the anhydrous phosphate mineral sidorenkite Na3Mn(PO4)(CO3)

• Published in: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
• Main Authors: Frost, Ray, Lopez Toro, Andres, Scholz, Ricardo, Belotti, Fernanda, Xi, Yunfei
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Elsevier 2015
• Subjects: carbonate; infrared spectroscopy; phosphate; raman spectroscopy; sidorenkite; Alluaiv; Kola Peninsula; kola peninsula
• Online Access: https://eprints.qut.edu.au/83664/

Sidorenkite is a very rare low-temperature hydrothermal mineral, formed very late in the crystallization of hyperagpaitic pegmatites in a differentiated alkalic massif (Mt. Alluaiv, Kola Peninsula, Russia). Sidorenkite Na3Mn(PO4)(CO3) is a phosphate–carbonate of sodium and manganese. Such a formula with two oxyanions lends itself to vibrational spectroscopy. The sharp Raman band at 959 cm−1 and 1012 cm−1 are assigned to the PO43− stretching modes, whilst the Raman bands at 1044 cm−1 and 1074 cm−1 are attributed to the CO32− stretching modes. It is noted that no Raman bands at around 800 cm−1 for sidorenkite were observed. The infrared spectrum of sidorenkite shows a quite intense band at 868 cm−1 with other resolved component bands at 850 and 862 cm−1. These bands are ascribed to the CO32− out-of-plane bend (ν2) bending mode. The series of Raman bands at 622, 635, 645 and 704 cm−1 are assigned to the ν4 phosphate bending modes. The observation of multiple bands supports the concept of a reduction in symmetry of the carbonate anion from D3h or even C2v.