NOVEL INSIGHTS INTO THE CHARACTERISTICS OF ERIONITE IN NEW ZEALAND

Erionite is a naturally occurring fibrous zeolite formed via hydrothermal alteration or diagenesis of volcanic rocks, commonly found in basalts and tuffs. The fibrous nature of erionite and its similarity to asbestos has led to cases of erionite exposure being linked to malignant mesothelioma. With erionite showing comparable or even higher carcinogenic potential than the regulated asbestos minerals. Initial health issues related to erionite exposure were observed in Cappadocia (Turkey), and more recently, occupational exposure concerns have emerged in the USA. While undisturbed erionite fibers are not considered a risk to human health, the International Agency for Research on Cancer (IARC) has classified erionite as a Group 1 carcinogen. In New Zealand, erionite has been found at numerous locations throughout both the North and South Islands in rock exposures. Some of these locations include (from north to south) Kaipara, Auckland, Taupo Volcanic Zone, Mount Somers, and the Moeraki coast. Given its carcinogenic nature, it is crucial to understand the distribution and character of the mineral fibres in New Zealand. This investigation into erionite in New Zealand is being undertaken using electron microscopy, Electron Microprobe Analysis, Raman spectroscopy, X-ray powder diffraction and the Rietveld method to identify erionite. Prominent examples identified so far include woolly erionite formed in vesicles of rhyolitic rock in the Canterbury region of the South Island, and asbestiform erionite in the Waitakere Group Volcanics in the Auckland region, of the North Island. Further research is ongoing to define the geological occurrence and characterise the chemistry, morphology, and mineralogy of all erionite samples from New Zealand in an attempt to outline the crystal chemistry of erionite from New Zealand and the related environmental risk hazards.