Apatite chemistry in Ce-Mn-Fe space

When considering felsic ore-related plutons (Fig. 3b), there is considerable overlap in the chemistry of apatite in the ore-related and non-ore producing systems. When considering only ore-producing systems, the apatites from the Conclurry district plot near the Ce end of the diagram this is not because they have unusually high Ce (3,550 ppm), but because they have such low Mn (0.04 wt % MnO) and Fe (0.04 wt % FeO) when compared to apatite from Climax-type porphyry Mo systems (4,950 ppm Ce, 0.10 wt % MnO, 0.30 wt% FeO). 

Apatite from mafic systems, irrespective of their relation to ore-systems, displays considerable variability and overlap on a plot of Ce-Mn-Fe (Fig. 3c), but apatite from systems not associated with ore-deposits may have lower concentrations of Mn. Carbonatites appear to have considerable exchange of Ce for Fe (Fig. 3d), a substitution that may require charge balance depending on the oxidation state of Fe substituting in the apatite. 

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