Erionite

The chemical composition of erionite is approximately represented by the formula . It can be differentiated into Erionite-Na, Erionite-K, and Erionite-Ca forms based on the most dominant component. Erionite has a hexagonal, cage-like structure composed of a framework of linked tetrahedra. It consists of white prismatic crystals in radiating groups of crystal fiber. Erionite absorbs up to 20% of its weight in water, has a specific gravity of 2.02 to 2.13, and has gas absorption, ion exchange, and catalytic properties that are highly selective and depend on the molecular size of the absorbed compounds. Zeolites, in general, have good thermal stability, rehydration kinetics, and water vapor adsorption capacity. ==Carcinogenicity==

Erionite is known to be a human carcinogen and is listed by the International Agency for Research on Cancer as a Group 1 Carcinogen. Descriptive studies have reported an excess of mortality from mesothelioma in individuals living in three Turkish villages where there was chronic exposure to erionite; only two cases of mesothelioma occurred in the control village, both in women born elsewhere. An excess of lung cancer also was reported in two of the three villages contaminated with erionite. Respirable erionite fibers were detected in air samples collected from the affected villages, and lung tissue samples collected from mesothelioma cases contained erionite fibers. A higher proportion of ferruginous bodies with a zeolite core were found in inhabitants of the contaminated villages than of those from the two control villages. ==Exposure==

Deposits of fibrous erionite are located in Arizona, Nevada, Oregon, and Utah, as well in urban Auckland in New Zealand. These zeolite beds may be up to thick and may lie in surface outcroppings. Erionite fibers have been detected in samples of road dust in Nevada and U.S. residents of the Intermountain West may be potentially exposed to fibrous erionite in ambient air. In the summer of 2009 North Dakota began a study of possible erionite exposure among residents. Erionite has also been identified in samples from the Tertiary Arikaree Formation in southeast Montana and northwest South Dakota. In the past, occupational exposure occurred from erionite mining and production operation. Nowadays potential occupational exposure to erionite usually occurs during the production and mining of other zeolites. Erionite was also reported to be a minor component in some commercial zeolites. Therefore, the use of other zeolites may result in potential exposure to erionite for the workers and the general population who use the zeolites in a variety of processes and products. Total dust exposures for miners in an open-pit zeolite mine that contained some erionite in Arizona ranged from 0.01 to 13.7 mg/m3; respirable dust in the mining area was 0.01 to 1.4 mg/m3. ==Gallery==

File:Eriomit Ca kamieniołom Boghill, Glengormley, Belfast, Irlandia Pn..jpg|Erionite-Ca File:Erionit K, Port Na Boe, Giants Causeway, Antrim Co., Irlandia Pn..jpg|Erionite-K File:Erionite, Offretite - Malpais Hill, Dudleyville, Pinal Co, Arizona, USA.jpg|Erionite and offretite File:Erionite-348875.jpg|Erionite in Arizona File:Erionite-161801.jpg|Erionite in Veneto ==See also==