Erioniit

Erioniit is a rare mineral belonging to the zeolite group. Zeolites are microporous aluminosilicate minerals. Erioniit is characterized by its fibrous or needle-like crystal habit and its distinctive chemical composition, which includes sodium, potassium, calcium, magnesium, aluminum, and silicon. Its chemical formula is often given as (Na, K, Ca, Mg)2[Al6Si10O28]·nH2O.

The mineral was first discovered in the United States and has since been found in a few other locations around the world, though it remains uncommon. Erioniit typically forms in volcanic rocks, particularly in cavities and fissures within altered basalt and rhyolite. It can also be found in sedimentary rocks. The formation process usually involves the interaction of hydrothermal fluids with volcanic glass or minerals.

Due to its fibrous nature, erioniit shares some physical similarities with other fibrous minerals, including asbestos. This has led to research and concern regarding its potential health effects. Exposure to airborne erioniit fibers has been linked to respiratory diseases, particularly mesothelioma, a rare cancer of the lining of the lungs. Consequently, areas where erioniit is found may be subject to environmental monitoring and regulations to prevent public exposure. Its rarity in nature and the health concerns associated with it mean that erioniit is not typically used for commercial purposes.