PINK LANTHANITE-(Nd) FROM WHITIANGA QUARRY, COROMANDEL PENINSULA, NEW ZEALAND

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 (Nd 0.63 La 0.59 Ce 0.35 Pr 0.15 Sm 0.10 Gd 0.069 Y 0.06 Eu 0.03 Dy 0.02 Ga 0.01) ⌺2.04 (CO 3) 3 •8H 2 O; the REE sum of 2.04 is due solely to rounding errors. The Þ nd represents the Þ rst 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.

Lanthanite-(Nd), Nd2(CO3)3·8H2O

“…It was not until Atencio et al (1989) analyzed a Bethlehem sample that it was found to be Nd-rich. Lanthanite-(Nd) has since been reported from other localities, including Curitiba, Brazil (Coutinho, 1955;Ansell et al, 1976;Cesbron et al, 1979;Roberts et al, 1980;Fujimori, 1981;Svisero & Mascarenhas, 1981); Saga Prefecture, Japan (Nagashima et al, 1986); Santa Isabel, São Paulo, Brazil (Coimbra et al, 1989); and Whitianga, Coromandel Peninsula, New Zealand (Graham et al, 2007). With the exception of those found in Whitianga, all lanthanite-(Nd) samples from these localities, including the one used in this study, exhibit a predominance of Nd with sub-equal La and a notable depletion of Ce.…”

“…For background to the lanthanite mineral group, see: Berzelius (1825); Blake (1853); Coutinho (1955); Shinn & Eick (1968); Ansell et al (1976);Dal Negro et al (1977); Cesbron et al (1979); Roberts et al (1980); Fujimori (1981); Svisero & Mascarenhas (1981); Nagashima et al (1986); Atencio et al (1989); Coimbra et al (1989); Graham et al (2007). For information on dawsonite, see: Corazza et al (1977).…”