Crystal structure refinement of aluminian lizardite-2H(2)

Well-crystallized euhedral crystals of aluminian lizardite-2H(2) (Mg2.35Fe0.062+Fe0.073+Al0.52) (Si1.41Al0.59)O-5.00(OH)(4.00) were found near Schio (Vicenza, Italy). To gain insight into the role of a high Al content lizardite, chemical analyses and single-crystal X-ray data collection were conducted. Structure refinement, completed in space group P6(3) (agreement factor R = 0.034), gives mean T-O values of 1.654 Angstrom and 1.664 Angstrom for T1 and T2 sites, respectively. The ditrigonal distortion of the six-membered tetrahedral ring is positive (alpha = +9.7 degrees), as expected for the 2H(2) polytype. The octahedral site has a mean bond length similar to that of the Mg-rich octahedra of amesite and distortion parameters similar to those of Al-rich octahedra.