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Titel |
Spectroscopic study of mimetite-vanadinite solid solution series - preliminary results |
VerfasserIn |
Urszula Janicka, Tomasz Bajda, Justyna Topolska, Maciej Manecki |
Konferenz |
EGU General Assembly 2014
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 16 (2014) |
Datensatznummer |
250090932
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Publikation (Nr.) |
EGU/EGU2014-5193.pdf |
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Zusammenfassung |
Mimetite Pb5(AsO4)3Cl and vanadinite Pb5(VO4)3Cl are minerals from the Pb-apatites
family which belong to the apatite supergroup. Most often they crystalize under hypergenic
conditions, in oxidation zones of Pb ore deposits, where they form paragenesis with
pyromorphite Pb5(PO4)3Cl. These minerals are used in the techniques of soils
reclamation. Their crystal structure allows substituting of metal cations as well as
of anionic complexes. Natural mimetite often contains admixture of phosphates
and/or vanadates. Similarly, vanadinite contains admixtures of phosphates and/or
arsenates.
Among the lead apatites, properties of the minerals from pyromorphite-mimetite solid
solution series are well known, while the knowledge about the mimetite-vanadinite series is
incomplete. The aim of this research was synthesis and spectroscopic characterization of
mimetite-vanadinite solid solution series.
Mimetite, vanadinite and their solid solution were synthesized from aqueous solutions by
dropwise mixing of Pb(NO3)2, Na3VO4, Na2HAsO4•7H2O and NaCl at 25 ºC and pH = 3.5.
Products of the syntheses were analyzed by X-Ray diffraction (XRD), Infrared absorption
spectroscopy (FTIR) and Raman spectroscopy.
The precipitates formed in the syntheses were identified by the XRD method as mimetite,
vanadinite and their solid solutions. Other crystalline phases were not present in synthetic
precipitates within the detection limit of XRD.
In the Mid-IR spectra of mimetite-vanadinite solid solutions series, bands characteristic
for vibrations of As-O bonds of the AsO4 tetrahedra and vibrations of V-O bonds of the VO4
tetrahedra were observed. The band corresponding to stretching ν3vibrations of AsO4 and
VO4 occured in the range 700-900 cm-1. In the Raman spectra, bands which are
characteristic for vibrations of As-O bonds of the AsO4 tetrahedra and vibrations of V-O
bonds of the VO4 tetrahedra were also observed. The bands attributed to vibrations in the
AsO4 tetrahedra appeared at 880-740 cm-1, 460-280 cm-1 and 220-120 cm-1. The bands
attributed to vibrations in the VO4 tetrahedra appeared in the ranges 830-820 cm-1 and
380-280 cm-1. Analysis of Mid-IR spectra and Raman spectra allowed to observe correlation
between changes in the position of the vibrational modes and the chemical compositions of
the studied samples.
The project was financed with resources of the National Science Centre of Poland,
granted based on decision no. DEC-2013/09/N/ST10/00677. |
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