Rietveld refinement of chapmanite SbFe_2Si_2O_8OH, a TO dioctahedral kaolinite-like mineral

摘要

Chapmanite Sb(OH)Fe_2(SiO_4)_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, singel-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.