Characteristics of rare-earth elements, Ba, Sr and Rb abundances in natural zeolites.

Abstract

Abundances of rare earth elements (REE), Ba, Sr and Rb were determined for several kinds of zeolites occurred in cavities of volcanic rocks from Japan with relevance to peculiar crystal chemical properties of zeolites. Because of the scarcity of REE data of zeolites, the following points would be noteworthy: (1) REE abundances for those zeolites are extremely low, ranging from about 0.01 to 0.1 in chondrite normalized unit; (2) Mutual fractionation among REE is rather small aside from small Eu and Ce anomalies; (3) Three different zeolite species from Maze area, Niigata Prefecture, show considerable resemblance with respect to REE, Ba and Sr concentrations. It is suggested that the REE incorporation in zeolites seems to be affected by their genetic process or formation environment rather than by difference in zeolite species. Moreover, relatively low REE abundances in zeolites may reflect extremely low REE abundances in the solutions from which those zeolites were precipitated. The Ce anomalies for the Maze samples show that those zeolites have not been deposited from magmatic solutions but from meteoric water.