Title: Precise determination of solubility constants in 5 – 65ºC temperature range and DHf, DGf, DS for apatites in of Ca-Pb-P-As-OH-Cl type.
Duration: 2011-2014
Principal Investigator: Maciej Manecki
Co-Investigators: Tomasz Bajda, Jakub Matusik
Funding agency: National Science Centre (Poland)
Project ID: Harmonia

The major accomplishments of the Project are:

– For the first time it was experimentally verified and confirmed that all apatites from solid solutions in question: a) hydrokxylpyromorphite Pb5(PO4)3(OH) – hydrokxylapatite Ca5(PO4)3(OH); b) hydroxylapatite Ca5(PO4)3(OH) – johnbaumite Ca5(AsO4)3(OH); and c) hydrokxylmimetite Pb5(AsO4)3(OH) – johnbaumite Ca5(AsO4)3(OH) can prezipitate stoichiometrically from aqueous solutions at normal environmental conditions.

– A model explaining systematic shifts in vibrational spectra of isomorphic solid solutions was proposed (for Raman and Infra-red spectroscopy) based on the bond strength and bond length as well as average mass of atoms located at substituted structural positions. As it was hypothesized, the model is universal and holds for all apatites.

– For the first time it was determined that in contrast to hexagonal crystalline structure of F- and Cl- varieties of Pb-apatites, their hydroxyl varieties are monoclinic. This is analogous to Ca-hydroxylapatites, but the effect on their stability (solubility) is opposite.

– For the first time it was determined that the solubility of pyromorphite Pb5(PO4­)3Cl is endothermic and the Ksp depends on the temperature following the nonlinear trend. This allowed for experimental determination of specific heat of formation Cp for pyromorphite.

– The role of carbonate substitution in Pb-apatites was precisely determined and correctly characterized, improving previously published results. For the first time the role of carbonates in arsenic lead apatites was described.

– Formation of precursors to lead-phosphate and lead-arsenate apatites was determined and characterized, including their solid solutions, isostructual with shultenite PbHAsO4 and phosphoshultenite PbHPO4.

Most important publications:

  • Topolska, J., Manecki, M., Bajda, T., Borkiewicz, O., Budzewski, P. (2016) Solubility of pyromorphite Pb5(PO4)3Cl at 5–65°C. Journal of Chemical Thermodynamics, 98, 282-287.
  • Kwaśniak-Kominek, M., Matusik, J., Bajda, T., Manecki, M., Rakovan, J., Marchlewski, T., Szala, B. (2015) Fourier transform infrared spectroscopic study of hydroxylpyromorphite Pb10(PO4)6OH2 – hydroxylmimetite Pb10(AsO4)6OH2 solid solution series. Polyhedron, 99, 103-111.
  • Giera, A., Manecki, M., Bajda, T., Rakovan, J., Kwaśniak-Kominek, M., Marchlewski, T. (2016) Arsenate substitution in lead hydroxyl apatites: a Raman spectroscopic study. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 152, 370-377.
  • Kwaśniak-Kominek M., Manecki M., Bajda T., Rakovan J. 2012. Pseudomorphic replacement of single cerussite PbCO3 crystals by hydroxylpyromorphite Pb5(PO4)3OH in phosphate solutions. EGU European Geosciences Union: General Assembly, Vienna, Austria, 22–27 April, 2012. In: Abstracts and Programme.
  • Kwaśniak M., Manecki M., Lempart M., Bajda T., Matusik J. 2012. Carbonate substitution in hydroxylpyromorphite Pb5(PO4)3OH. EMC 2012: European Mineralogical Conference, Frankfurt, Germany, 2–6 September, 2012. In: Theme 6 – Mineralogical crystallography: Handling structural complexity: theoretical and experimental methods applied to unravel structural hierarchies.
  • Dziura A., Kwaśniak-Kominek M., Manecki M., Bajda T. Low temperature synthesis and thermodynamic stability of fluorpyromorphite Pb5(PO4)3F at 5-65°C. Herlandia 2013: XIV International Conference of Young Geologists Herl’any 2013. Svätý Jur, Slovak Republic, 4–6 April, 2013. In: Geology, Geophysics & Environment, 38: 465.

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