Erioniitti

Erioniitti, or erionite, is a natural fibrous mineral of the zeolite group. It forms slender, needle-like fibers that can occur in bundles, giving it a fibrous habit similar in appearance to some asbestos minerals. The composition is typically described as a hydrated aluminosilicate with alkali metals, commonly written as (K, Na)2Al4Si27O72·28H2O, with calcium and magnesium and other cations able to substitute in natural samples.

Occurrence and formation: Erioniitti forms in volcanic rocks, especially in pyrogenic tuffs and altered zeolite-rich rocks produced by hydrothermal processes. It is associated with other zeolites and can be found in arid or semi-arid volcanic environments. Notable historical occurrences have been described in Cappadocia, Turkey, where erionite-rich rocks have drawn scientific attention due to health concerns, though erionite has been reported in other regions as well.

Health effects: Inhalation of erionite fibers is strongly associated with respiratory diseases, including malignant mesothelioma, a cancer of the lining of the lungs and other organs. The risk is related to fiber dimensions, biopersistence, and exposure duration. Because of its health hazards, erioniitti-containing materials are treated with caution, and handling fibrous zeolites is generally discouraged without appropriate protection.

Uses and regulation: Due to its fibrous nature and health risks, erioniitti is not used commercially in a way similar to more stable minerals. In many contexts, activities involving erioniitti-bearing rocks are subject to strict safety guidelines to minimize airborne fiber exposure. Researchers study erioniitti to understand zeolite mineralogy and to assess environmental and health implications of natural fibrous minerals.