title: The molecular structure of the vanadate mineral mottramite [PbCu(VO4)(OH)] from Tsumeb, Namibia--a vibrational spectroscopic study.
abstract: We have studied a mineral sample of mottramite PbCu(VO4)(OH) from Tsumeb, Namibia using a combination of scanning electron microscopy with EDX, Raman and infrared spectroscopy. Chemical analysis shows principally the elements V, Pb and Cu. Ca occurs as partial substitution of Pb as well as P and As in substitution to V. Minor amounts of Si and Cr were also observed. The Raman band of mottramite at 829 cm(-1), is assigned to the ν1 symmetric (VO4(-)) stretching mode. The complexity of the spectra is attributed to the chemical composition of the Tsumeb mottramite. The ν3 antisymmetric vibrational mode of mottramite is observed as very low intensity bands at 716 and 747 cm(-1). The series of Raman bands at 411, 439, 451 cm(-1) and probably also the band at 500 cm(-1) are assigned to the (VO4(-)) ν2 bending mode. The series of Raman bands at 293, 333 and 366 cm(-1) are attributed to the (VO4(-)) ν4 bending modes. The ν3, ν3 and ν4 regions are complex for both minerals and this is attributed to symmetry reduction of the vanadate unit from Td to Cs.
authors: 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: Ray L
authors: RL
authors: Frost
authors: School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia.
authors: Yunfei
authors: Y
authors: Xi
authors: School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia.
authors: Andrés
authors: A
authors: López
authors: Geology Department, School of Mines, Federal University of Ouro Preto, Campus Morro do Cruzeiro, Ouro Preto, MG, 35, 400-00, Brazil.
authors: Lívia
authors: L
authors: Corrêa
authors: Geology Department, School of Mines, Federal University of Ouro Preto, Campus Morro do Cruzeiro, Ouro Preto, MG, 35, 400-00, Brazil.
authors: Ricardo
authors: R
authors: Scholz
mesh_terms: D003300:Copper / Q000737:chemistry*; D003460:Crystallization; D007854:Lead / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D008903:Minerals / Q000737:chemistry*; D009276:Namibia; D013052:Spectrometry, X-Ray Emission; D013059:Spectrum Analysis, Raman; D014638:Vanadates / Q000737:chemistry*; D014732:Vibration
chemical_list: D008903:Minerals; D007854:Lead; D014638:Vanadates; D003300:Copper
keywords: Apatite; Descloizite; Infrared spectroscopy; Mottramite; Pyromorphite; Raman microscopy