Erionite is a naturally occurring fibrous mineral that belongs to a group of minerals called zeolites. It usually is found in

volcanic ash Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, produced during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to r ...

that has been altered by weathering and ground water. Erionite forms brittle, wool-like fibrous masses in the hollows of rock formations and has an internal molecular structure similar to chabazite. This mineral is likely as toxic as

asbestos Asbestos ( ) is a group of naturally occurring, Toxicity, toxic, carcinogenic and fibrous silicate minerals. There are six types, all of which are composed of long and thin fibrous Crystal habit, crystals, each fibre (particulate with length su ...

; however, erionite is not currently regulated by the U.S. Environmental Protection Agency and there are no occupational exposure limits for erionite fibers. Erionite was first described by A.S. Eakle in 1898, as white woolly fibrous masses in cavities in

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture (geology), texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained matri ...

lava near Durkee, Oregon. It was originally thought to be another relatively rare zeolite named offretite, which is very similar to erionite in appearance and chemical composition.

Properties

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 The International Agency for Research on Cancer (IARC; ) is an intergovernmental agency forming part of the World Health Organization of the United Nations. Its role is to conduct and coordinate research into the causes of cancer. It also cance ...

as a Group 1 Carcinogen. The prevalence of malignant

pleural The pleural cavity, or pleural space (or sometimes intrapleural space), is the potential space between the pulmonary pleurae, pleurae of the pleural sac that surrounds each lung. A small amount of serous fluid, serous pleural fluid is maintained ...

and peritoneal mesothelioma due to erionite exposure in the

Cappadocia Cappadocia (; , from ) is a historical region in Central Anatolia region, Turkey. It is largely in the provinces of Nevşehir, Kayseri, Aksaray, Kırşehir, Sivas and Niğde. Today, the touristic Cappadocia Region is located in Nevşehir ...

region of Central Anatolia is very high. 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. Erionite is reportedly present in the local volcanic tuff. There is sufficient evidence of carcinogenicity of erionite in experimental animals. Rats exposed to erionite by inhalation or injection ( intrapleural or intraperitoneal) and

mice A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...

exposed by intraperitoneal injection had a high incidence of mesothelioma. Additionally, although carcinogenic properties of erionite have been discovered by investigating the erionite found in Central Anatolia, Turkey, no difference in their carcinogenic capacity has been observed when it was compared to the erionite obtained in North Dakota, USA.

Exposure

Deposits of fibrous erionite are located in

Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...

Nevada Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...

Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...

, and

Utah Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...

, as well in urban

Auckland Auckland ( ; ) is a large metropolitan city in the North Island of New Zealand. It has an urban population of about It is located in the greater Auckland Region, the area governed by Auckland Council, which includes outlying rural areas and ...

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 North Dakota ( ) is a U.S. state in the Upper Midwest, named after the indigenous Dakota people, Dakota and Sioux peoples. It is bordered by the Canadian provinces of Saskatchewan and Manitoba to the north and by the U.S. states of Minneso ...

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. Erionite is held responsible for the high incidence of

asbestosis Asbestosis is long-term inflammation and pulmonary fibrosis, scarring of the human lung, lungs due to asbestos fibers. Symptoms may include shortness of breath, cough, wheezing, and chest pain, chest tightness. Complications may include lung canc ...

and various forms of

lung cancer Lung cancer, also known as lung carcinoma, is a malignant tumor that begins in the lung. Lung cancer is caused by genetic damage to the DNA of cells in the airways, often caused by cigarette smoking or inhaling damaging chemicals. Damaged ...

within the Turkish village of Tuzkoy near Nevsehir in the popular tourist region of Cappadoccia.

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 Veneto, officially the Region of Veneto, is one of the 20 regions of Italy, located in the Northeast Italy, north-east of the country. It is the fourth most populous region in Italy, with a population of 4,851,851 as of 2025. Venice is t ...

References

{{USGovernment, url=https://ntp.niehs.nih.gov/ntp/roc/content/profiles/erionite.pdf, title=Erionite

External links