Abstract
Lanthanite-(Nd) occurs in tuffaceous, altered andesitic agglomerate in the Whitianga quarry, Coromandel Peninsula, New Zealand. The usual platy habit is represented, together with more unusual blocky equant crystals. The former show the new forms (201), (102) and (111), and the latter, (111). ICP–MS analyses show that the distribution of REE (and Ga) is consistent with the formulation (Nd0.63La0.59Ce0.35Pr0.15Sm0.10Gd0.069Y0.06Eu0.03Dy0.02Ga0.01){sum} 2.04(CO3)3·8H2O; the REE sum of 2.04 is due solely to rounding errors. The find represents the first occurrence of this rare mineral in New Zealand. The mineral formed under comparatively oxidizing conditions. The REE are probably scavenged by warm waters circulating through underlying greywackes of the Manaia Hill Group. We also characterized the lanthanite-(Nd) by X-ray diffraction (powder method) and Raman spectroscopy.