CRYSTAL-STRUCTURE OF LIZARDITE-1T FROM ELBA, ITALY

Euhedral lizardite-1T occurs in the Monte Fico quarries, Elba Island, Italy. The composition is Mg2.74Fe0.16Al0.09Si1.93Al0.07O5(OH)4. Unit- cell parameters, for two crystals, each with space group P31m, are a = 5.338(4) and c = 7.257(6) and a = 5.330(4) and c = 7.269(6) angstrom. The crystal structures were refined to R(tot) = 0.034 and 0.046, usin g 251 and 849 independent reflections, respectively. The topology dete rmined from previous refinements is confirmed; in particular, the tetr ahedral rotation angle is negative (alpha = -2.8 and -2.7-degrees), as expected for the 1T polytype.