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Re-investigation of the crystal structure of whewellite [Ca(C2O4)·H2O] and the dehydration mechanism of caoxite [Ca(C2O4)·3H2O]

Published online by Cambridge University Press:  05 July 2018

T. Echigo ,
M. Kimata ,
A. Kyono ,
M. Shimizu  and
T. Hatta
T. Echigo*
Affiliation:
Earth Evolution Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba 305-8572, Japan
M. Kimata
Affiliation:
Earth Evolution Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba 305-8572, Japan
A. Kyono
Affiliation:
Earth Evolution Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba 305-8572, Japan
M. Shimizu
Affiliation:
Earth Evolution Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba 305-8572, Japan
T. Hatta
Affiliation:
Japan International Research Center for Agricultural Sciences, Independent Administrative Institute, Ohwashi 1-1, Tsukuba 305-8686, Japan
*
*E-mail: [email protected]
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Abstract

The crystal structure of whewellite [Ca(C2O4)·H2O] and the dehydration mechanism of caoxite [Ca(C2O4)·3H2O] have been studied by means of differential thermal analysis, X-ray diffraction (powder and single-crystal) analysis and infrared analysis. The first and second analyses confirmed the direct transformation of caoxite into whewellite without an intermediate weddellite [Ca(C2O4)·2H2O] stage. Infrared spectra obtained from caoxite, weddellite and whewellite emphasize the similarity of the O–H-stretching band and O–C–O-stretching band in whewellite and caoxite and the unique bands of weddellite. The structure refinement at low temperature (123 K) reveals that all the hydrogen atoms of whewellite form hydrogen bonds and the two water molecules prop up the crystal structure by the hydrogen bonds that cause a strong anisotropy of the displacement parameter.

Comparing the structural features of whewellite with those of weddellite and caoxite suggests that caoxite and whewellite have a sheet structure consisting of Ca2+ ions and oxalate ions although weddellite does not. It is additionally confirmed that the sheets of caoxite are corrugated by hydrogen bonds but whewellite has flat sheets. The corrugated sheets of caoxite would be flattened by dehydration so the direct transformation of caoxite into whewellite would not occur via weddellite. Essential for this transformation is the dehydration of interlayered water molecules in caoxite leading to the building of the crystal structure of whewellite on its intralayered water molecules. The difference in conformation of water molecules between those two crystal structures may explain the more common occurrence of whewellite than of caoxite in nature.

Keywords

whewellitecaoxite, weddellitedehydration mechanismcrystal structureX-ray diffractioninfrared analysisdifferential thermal analysis
Type
Research Article
Information
Mineralogical Magazine , Volume 69 , Issue 1 , February 2005 , pp. 77 - 88
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2005

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References

Arnott, H.J., Pautard, E.G.F. and Steinfink, H. (1965) Structure of calcium oxalate monohydrate. Nature, 208, 1197–1198.CrossRefGoogle Scholar
Basso, R., Lucchetti, G., Zefiro, L. and Palenzona, A. (1997) Caoxite, Ca(H2O)3(C2O4), a new mineral from the Cerchiara mine, northern Apennines, Italy. Neues Jahrbuch für Mineralogie, Monatshefte, 84–96Google Scholar
Beurskens, P.T., Admiraal, G., Bosman, W.P., de Gelder, P., Israel, R. and Smits, J.M.M. (1999) The DIRDIF-99 program system. Technical report of the Crystallography Laboratory, University of Nijmegen, The Netherlands.Google Scholar
Cocco, G. (1961) The structure of whewellite. Atti delta Accademia nazionale dei Lincei. Classe di scienze fisiche, matematiche e naturali. Rendiconti. Serie ottava, 31, 292–298.Google Scholar
Cocco, G. and Sabelli, C. (1962) Structure of whewellite with electronic computer. Atti della Societá Toscana di scienze naturali. Processi verbali, 69, 289—298.Google Scholar
Deganello, S. and Piro, E.O. (1981) The crystal structure of calcium oxalate monohydrate (whewellite). Neues Jahrbuch für Mineralogie, Monatshefte, 81—88.Google Scholar
Deganello, S., Kampf, R.A. and Moore, B.P. (1981) The crystal structure of calcium oxalate trihydrate: Ca(H2O)3(C2O4). American Mineralogist, 66, 859–865.Google Scholar
Frost, R.L. and Weier, M.L. (2003) Thermal treatment of weddellite — a Raman and infrared emission spectroscopic study. Thermochimica Acta, 406, 221–232.CrossRefGoogle Scholar
Frost, R.L. and Weier, M.L. (2004) Thermal treatment of whewellite — a thermal analysis and Raman spectroscopic study. Thermochimica Acta, 409, 79–85.CrossRefGoogle Scholar
Gaines, R.V., Skinner, H.C.W., Foord, E.E., Mason, B. and Rosenzweig, A. (1997) Dana's New Mineralogy: the System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, 8th edition. 1011 pp., John Wiley & Sons, New York.Google Scholar
Hoffman, W. (1961) On the crystal structure of whewellite, Ca(C2O4)H2O. Fortschritte der Mineralogie, 39, 346–347.Google Scholar
Kloprogge, T.J., Bostrom, E.T. and Weiler, L.M. (2004) In situ observation of the thermal decomposition of weddellite by heating stage environmental scanning electron microscopy. American Mineralogist, 89, 245–248.CrossRefGoogle Scholar
Leavens, B.P. (1968) New data on whewellite. American Mineralogist, 53, 455–463.Google Scholar
Morishige, K., Yoshida, M., Murakami, H., Senoh, N., Kamei, K. and Nishikawa, Y. (1999) Characterization of calcium oxalate hydrate precipitations by the infrared spectrum and X-ray powder diffracton method and its urinary calculi analysis. Journal of the Faculty of Science and Technology, Kinki University, 35, 53–59.(in Japanese with English abstract).Google Scholar
Simons, E.L. and Newkirk, A.E. (1964) Calcium oxalate monohydrate guide to the interpretation of thermogravimetric measurement. Talanta, 11, 549—571.CrossRefGoogle Scholar
Stering, C. (1965) Crystal-structure analysis of weddellite, CaC2O4(2+x)H2O. Acta Crystallographica, 18, 917–921.CrossRefGoogle Scholar
Tazzoli, V. and Domeneghetti, C. (1980) The crystal structures of whewellite and weddellite: re-examina¬tion and comparison. American Mineralogist, 65, 327–334.Google Scholar
Tomažic, B. and NancoUas, G.H. (1979) The kinetics of dissolution of calcium oxalate hydrates. Journal of Crystal Growth, 46, 355–361.Google Scholar
Watkin, D.J., Prout, C.K., Carruthers, J.R. and Betteridge, P.W. (1996) Crystals. Issue 10, Chemical Crystallography Laboratory, Oxford, UK.Google Scholar