Tetrahedrally-coordinated Al in Mn-rich, Li- and Fe-bearing olenite from Eibenstein an der Thaya, Lower Austria: A chemical and structural investigation

摘要

Chemical analysis (including light elements) of a Mn-rich tourmaline from a recently discovered locality near Eibenstein an der Thaya, Lower Austria, characterizes the sample as Mn-rich, Li-, and Fe-bearing olenite. Chemical analysis in combination with the crystal structure (a = 15.9325(5) A, c = 7.1308(4) A, R = 0.022) demonstrate that significant amounts of ~[4]Al (0.33 apfu) occur at the T site of this Mn-rich olenite, in very good agreement with the amount of ~[4]Al predicted by the distance of approx 1.626 A. Significant amounts of ~[4]Al are for the first time verified in Mn-rich olenite. Interestingly, the Li content with 0.79 wt. percent Li_2O of this sample is relatively low for Mn-bearing tourmaline. The optimized formula (chemical data in combination with refinement of the site scattering) of this Mn-rich, Li- and Fe-bearing olenite is ~X(Na_(0.827)Ca_(0.022)K_(0.004)square_(0.147)) ~Y(Al_(1.349)Mn_(0.676)Li_(0.517)Fe_(0.227)Ti_(0.038)Mg_(0.002)Zn_(0.002)square_(0.189)) ~ZAl_(6.00) B_(3.00) ~T(Si_(5.675)Al_(0.325)) O_(27)[(OH)_(3.368)F_(.498)O_(0.134)].