The lanthanides and yttrium in minerals of the apatite group - an analysis of the available data

Apatites of sedimentary marine phosphorites occupy a special position, being relatively depleted in Ce and relatively enriched in yttrium and the heavy lanthanides, consequences of their deposition from sea water or marine muds. Apatites associated with iron ores resemble those of carbonatites, alkalic ultramafic, and ultramafic rocks, in being enriched in the light lanthanides and depleted in the heavy ones. The distribution of lanthanides in apatite is clearly dependent on the nature of the host rock. Although a given analysis of the lanthanides may not permit certain identification of the host rock, it can indicate choice of probable host rocks. However, for some areas of the distribution field, the host rock is clearly designated. (orig./PW)