Scolecite, Part I: Refinement of high-order data, separation of internal and external vibrational amplitudes from displacement parameters

A single crystal of scolecite, CaAl2Si3O10· 3H2O, was studied by X-ray diffraction methods at room temperature. The intensities were measured with MoKα radiation (λ=0.71069 A) in a complete sphere of reflection up to sinθ/λ=0.9 A−1. The structure was refined in the pseudo-orthorhombic setting of space group F1d1 instead of the conventional setting Cc for better comparison with natrolite (Fdd2). The cell parameters are: a=18.502(1) A, b=18.974(2) A, c=6.525(1) A, β=90.615(7)°, V=2290.6(3) A3, Z=8. A refinement of high-order diffraction data yielded residuals of R(F)=0.9%, R w (F)=0.9%, GoF=1.73 for 1831 high-angle reflections (0.7≤sinθ/λ≤0.9 A−1) and R(F)=1.2%, R w (F)=1.4%, GoF=3.22 for all…