Optical absorption spectra of Mn (super 3+) ions in vesuvianites from Lower Silesia, Poland

Lilac, yellow and pink crystals of Mn-bearing (up to 1.10 wt.%) vesuvianites from the Jordanow rodingitic rocks in Lower Silesia were studied by optical and IR methods. Absorption spectra of the lilac samples show an intense broad band at 18500 cm (super -1) in the E ^ c polarization and weak bands at 23100, 18500 and 12500 cm (super -1) in the E c polarization. The spectra of the yellow vesuvianites have a strong E ^ c polarized band near 23600 cm (super -1) and weak bands at 23900, 22700 and 20100 cm (super -1) in the E c polarization. The spectra of the pink variety results from superposition of Mn (super 3+) bands in the spectra of the lilac and yellow vesuvianites. The spectra of the yellow vesuvianite are due to Mn (super 3+) ions occupying the five-fold-coordinated B sites; the dominant absorption band at 23600 cm (super -1) is assigned to the only symmetry-allowed transition (super 5) B (sub 1) ->> (super 5) E in Mn (super 3+) ions. The spectra of the lilac variety can be assigned to Mn (super 3+) ions in the distorted AlFe octahedra or also in B sites, which have different B-O (sub 10) distances. The distribution of Mn (super 3+) in non-equivalent structural sites of these vesuvianites may be the result of different T of crystallization and state of ordering; this is supported by IR studies.