title: A vibrational spectroscopic study of the silicate mineral inesite Ca2(Mn,Fe)7Si10O28(OH)⋅5H2O.
abstract: We have studied the hydrated hydroxyl silicate mineral inesite of formula Ca2(Mn,Fe)7Si10O28(OH)⋅5H2O using a combination of scanning electron microscopy with EDX and Raman and infrared spectroscopy. SEM analysis shows the mineral to be a pure monomineral with no impurities. Semiquantitative analysis shows a homogeneous phase, composed by Ca, Mn(2+), Si and P, with minor amounts of Mg and Fe. Raman spectrum shows well resolved component bands at 997, 1031, 1051, and 1067 cm(-1) attributed to a range of SiO symmetric stretching vibrations of [Si10O28] units. Infrared bands found at 896, 928, 959 and 985 cm(-1) are attributed to the OSiO antisymmetric stretching vibrations. An intense broad band at 653 cm(-1) with shoulder bands at 608, 631 and 684 cm(-1) are associated with the bending modes of the OSiO units of the 6- and 8-membered rings of the [Si10O28] units. The sharp band at 3642 cm(-1) with shoulder bands at 3612 and 3662 cm(-1) are assigned to the OH stretching vibrations of the hydroxyl units. The broad Raman band at 3420 cm(-1) with shoulder bands at 3362 and 3496 cm(-1) are assigned to the water stretching vibrations. The application of vibrational spectroscopy has enabled an assessment of the molecular structure of inesite to be undertaken.
authors.affiliation: School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia. Electronic address: r.frost@qut.edu.au.
authors.forename: Ray L
authors.initials: RL
authors.lastname: Frost
authors.affiliation: School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia.
authors.forename: Andrés
authors.initials: A
authors.lastname: López
authors.affiliation: School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia.
authors.forename: Yunfei
authors.initials: Y
authors.lastname: Xi
authors.affiliation: Geology Department, School of Mines, Federal University of Ouro Preto, Campus Morro do Cruzeiro, Ouro Preto, MG 35,400-00, Brazil.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Scholz
mesh_terms: D017640:Silicates / Q000737:chemistry*
chemical_list: D017640:Silicates
keywords: Inesite; Infrared spectroscopy; N’chwaning mine; Raman spectroscopy; Silicate