STRUCTURAL STUDIES OF BRITTLE MICAS (I) THE STRUCTURE OF XANTHOPHYLLITE REFINED

Abstract

The crystal structure of xanthophyllite was refined by least squares with 384 F₀(hkl). The results established the detailed configuration of the (Al₃Si)O₁₀ sheet and showed an evidence of ordering of cations in the octahedral positons. The average bond lengths determined are: Al₃Si-O, 1.730±0.014Å; Al, Mg-O, 2.016±0.011Å; Mg-O, 2.072±0.014Å; Ca-O, 2.410±0.012Å.