Chapmanite, Sb(OH)Fe-2(SiO4)(2) is a rare mineral that generally occurs as yellow coatings on rocks from antimony mines. The very small dimensions of the crystals prevented X-ray, single-crystal study of the mineral whose structure was derived through high voltage electron diffraction (Zhukhlistov and Zvyagin, 1977). The present study confirm the correctness of the structure determined by those authors and also shows the effectiveness of the Rietveld method in the case of highly diluted phases. The structure of chapmanite is similar to that of kaolinite with two major differences: (a) the dioctahedral sheet of chapmanite contains Fe3+ instead of Al3+; (b) chapmanite has Sb3+ cations grasped to the octahedral sheet, on the opposite side with respect to the tetrahedral sheet. (C) 1998 International Centre for Diffraction Data.
|Autori:||BALLIRANO P.; MERLINO S; PERCHIAZZI N.; MARAS A.; MARCHETTI F.|
|Titolo:||Rietveld refinement of chapmanite SbFe2Si2O8(OH), a TO dioctahedral kaolinite-like mineral|
|Anno del prodotto:||1998|
|Appare nelle tipologie:||1.1 Articolo in rivista|