Luminescence spectroscopy of Mn²⁺rock-forming carbonates

Cathodoluminescence emission spectra and luminescence excitation spectra of Mn 2+ in calcites, dolomites, magnesites, a manganocalcite and a rhodochrosite have been measured at both room temperature and 77 K. Ligand-field parameters have been calculated from the excitation spectra which reflect the size of the metal cation site in which the Mn 2+ ion resides. The technique of luminescence excitation spectra has enabled the absorption profile of Mn 2+ in Mg and Ca sites in dolomite to be separately determined. The variation of the distribution of Mn 2+ between Mg and Ca sites in dolomites is demonstrated and discussed in terms of a simple model. It is concluded that the distribution of Mn 2+ in dolomites may well provide information about its conditions of formation and/or subsequent alteration.