Luminescence Spectroscopy of Mn2+ Centres in Rock-Forming Carbonates

G. Walker, O. E. Abumere* and B. Kamaluddin
Dept. of Pure & Applied Physics, UMIST, Manchester M60 1QD
*Present addresse: Physics Dept. University of Port Harcourt, Nigeria
Present addresse:Physics Dept., University of Malaysia, Lembah Pentai, Kuala Lumpur, Malaysia.

Abstract: Cathodoluminescence emission spectra and luminescence excitation spectra of Mn2+ 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 Mn2+ ion resides. The technique of luminescence excitation spectra has enabled the absorption profile of Mn2+ in Mg and Ca sites in dolomite to be separately determined. The variation of the distribution of Mn2+ between Mg and Ca sites in dolomites is demonstrated and discussed in terms of a simple model. It is concluded that the distribution of Mn2+ in dolomites may well provide information about its conditions of formation and/or subsequent alteration.

Keywords: cathodoluminescence • manganese • carbonates • dolomite

Mineralogical Magazine; April 1989 v. 53; no. 370; p. 201-211; DOI: 10.1180/minmag.1989.053.370.07
© 1989, The Mineralogical Society
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