Original paper
Optical absorption spectra of Mn3+ ions in vesuvianites from Lower Silesia, Poland
Platonov, Alexej N.; Żabiński, Witold; Sachanbiński, Michał
European Journal of Mineralogy Volume 7 Number 6 (1995), p. 1345 - 1352
31 references
published: Dec 22, 1995
manuscript accepted: Jun 6, 1995
manuscript received: Jun 15, 1994
DOI: 10.1127/ejm/7/6/1345
Abstract
Abstract Lilac, yellow and pink, small crystals of manganese-bearing (up to 1.10 wt.%) vesuvianites from Lower Silesia, Poland, were studied by optical and IR spectroscopic methods. Absorption spectra of the lilac sample show an intense, broad band at 18500 cm-1 in the E⟂c-polarization and weak bands at 23 100 cm-1, 18500 cm-1 and 12500 cm-1 in the Ellc-polarization. The spectra of the yellow vesuvianites have a strong E II c-polarized band near 23600 cm-1 and weak bands at 23900 cm-1, 22700 cm-1 and 20100 cm-1 in the E II c-polarization. The spectra of the pink variety result from superposition of Mn3+-bands in the spectra of the lilac and yellow vesuvianites. It has been concluded that spectra of the yellow vesuvianite studied are due to Mn3+ ions occupying the fivefold-coordinated B-sites (C4V symmetry). The dominating absorption band 23600 cm-1 is assigned to the only symmetry-allowed transitions 5B1 ->5E in Mn3+ ions. The spectra of the lilac variety can be assigned to Mn3+ ions in the distorted AlFe-octahedra or also in B-sites, which have different B-Oio distances. The distribution of Mn3+ in non-equivalent structural positions of the vesuvianites studied may be the result of different temperatures of crystallization and of the state of ordering, which is supported by IR spectroscopic investigations
Keywords
Mn-bearing vesuvianite • optical absorption spectra • colour of vesuvianite • IR spectra