Detection of trace amounts of erionite using X-ray powder diffraction; erionite in tuffs of Yucca Mountain, Nevada, and central Turkey

Recent data suggest that this natural zeolite may be more tumourigenic than asbestos minerals. Because of its potential biological importance a technique has been developed to facilitate detection of erionite in tuffaceous rocks to a lower limit of detection of between 100-500 ppm. Application of the methods to tuffs from central Turkey allowed improved detection and more accurate quantification compared with previous SEM examinations. Use of the methods with tuffs from Yucca Mt, the potential site for the USA's first high-level radioactive waste repository, showed that erionite occurs sporadically. It is found only in the altered zone above the lower vitrophyre of the Topopah Spring member; this zone is anomalous in that it contains a variety of zeolites which are either rare or absent in other Yucca Mt tuffs. It seems that erionite is restricted to fractures and must have formed under unusual and variable conditions in the altered zone.