Crystallographic study of the mineral ferroan clinozoisite from three localities of Northern Greece

Abstract

Samples of the mineral ferroan clinozoisite from three localities of Greece (Paranesti-Drama, Xanthi, and Petritsi-Serres), with chemical formula Ca2Al3−xFexSi3O13H (x=0.55, 0.58, and 0.46, respectively), were measured by X-ray powder diffraction, using CoKa radiation. The PDF and bibliographic information were used in order to identify additional phases in the samples. Refinement combined with PDF resulted in the following: ferroan clinozoisite (100%) for the first sample, ferroan clinozoisite (97%) and malladrite (3%) for the second one, and ferroan clinozoisite (75%), clinopyroxene (20%), and malladrite (5%) for the third one. The crystal structure refinement was performed by the “Powder profile analysis (Rietveld)”. P21/m space group was chosen for the ferroan clinozoisite phases, with unit cell constants a=8.8919(5) Å, b=5.6260(3) Å, c=10.1570(6) Å, β=115.418(3)° (Paranesti), a=8.8944(7) Å, b=5.6394(4) Å, c=10.1626(8) Å, β=115.400(5)° (Xanthi) a=8.8965(8) Å, b=5.6372(4) Å, c=10.1595(9) Å, β=115.411(6)° (Petritsi) almost similar for the three samples, while the final R-p factors were 0.069, 0.064, and 0.063, respectively.