erionite

Erionite is a natural fibrous zeolite mineral, a hydrated aluminosilicate belonging to the zeolite group. It forms slender, acicular crystals that commonly occur in radiating or fibrous aggregates. Erionite is typically found in volcanic rocks such as altered ash beds and tuffs where groundwater interactions promote zeolite formation. The name derives from the Greek erion, wool, for its woolly habit.

Chemically, erionite features a framework of aluminum, silicon, and oxygen balanced by alkali and alkaline-earth cations, most notably sodium and potassium with calcium or magnesium, and water molecules occupying the porous zeolite structure. Its composition is variable and reflects the specific geochemical environment of each deposit.

In terms of properties, erionite is a fragile mineral with a woolly or fibrous appearance. The fibers can be airborne dusts, which has implications for health and safety in mining and research contexts. As with other fibrous minerals, handling erionite requires appropriate precautions to minimize inhalation exposure.

Health considerations are a central aspect of erionite. Inhalation of erionite fibers has been linked to an increased risk of mesothelioma and other lung diseases in affected populations, sometimes at rates higher than those associated with other silica-based fibers. Because of these hazards, erionite is not used for commercial applications and is treated as a hazardous mineral in occupational settings.

Occurrence locations include Cappadocia in central Turkey, with additional reports in other volcanic-terrane deposits worldwide. It commonly occurs alongside other zeolites in altered volcanic tuffs and is of interest primarily to mineralogists and geologists rather than for industrial use.