Rare-Earth abundances in some ultramafic rocks

A survey has been made of the abundances of the rare earths (REE) in ultramafic rocks. Samples analyzed were taken from alpine regions, layered intrusions, basaltic nodules, and kimberlite pipes. A wide range of REE concentrations and relative abundances was found. Crystal chemical restrictions and type of field occurrence appear to affect REE abundances in ultramafic rocks. Kimberlites are characteristically quite enriched in the light REE compared to the REE distribution in chondritic meteorites. The only ultramafic rocks found to be relatively depleted in the light REE were those from some of the alpine environments sampled. Some ultramafic rocks from layered intrusions had nearly chondritic REE distributions.