gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1996.060.400.03 Mineralogy Minor and Trace Element Chemistry of Carbonates, Apatites and Magnetites in Some African Carbonatites Dawson J. B. Department of Geology and Geophysics, University of Edinburgh, West Mains Road, Edinburgh EH9 3JW, UK Steele I. M. Smith J. V. Department of Geophysical Sciences, University of Chicago, 5734 S. Ellis Ave, IL 60637, USA Rivers M. L. Department of Geophysical Sciences and Consortium for Advanced Radiation Sources, University of Chicago, 5734 S. Ellis Ave, Chicago, IL 60637, USA 6 1996 60 400 415 425 30 10 1995 14 12 1995 Copyright © 1996, The Mineralogical Society 1996 Abstract

In calcites and dolomites in seven African carbonatites, SrO, FeO and MnO occur in concentrations from 1 to 2 wt.%, whereas Ce, Y, Cu and Zn occur only at the ppm level. Sr, Ce and Y partition preferentially into calcite relative to co-existing dolomite, whereas Fe and Mn favour dolomite. Sr partitions preferentially into calcite relative to co-exisiting apatite, but the light rare-earth elements partition into apatite. Magnetite from Kerimasi contains up to 13 wt.% MgO and 6 wt.% MnO, extending the known ranges in composition of magnetites from carbonatites.

 Keywords mineral chemistry carbonatite carbonate apatite magnetite Africa