Erionite is a naturally occurring fibrous mineral that belongs to a group of minerals called

zeolites Zeolites are microporous, crystalline aluminosilicate materials commonly used as commercial adsorbents and catalysts. They mainly consist of silicon, aluminium, oxygen, and have the general formula ･y where is either a metal ion or H+. These p ...

. It usually is found in

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

that has been altered by weathering and

ground water Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...

. Erionite forms brittle, wool-like fibrous masses in the hollows of rock formations and has an internal molecular structure similar to chabazite. Some properties of erionite are similar to the properties of

asbestos Asbestos () is a naturally occurring fibrous silicate mineral. There are six types, all of which are composed of long and thin fibrous crystals, each fibre being composed of many microscopic "fibrils" that can be released into the atmosphere b ...

; however, erionite is not currently regulated by the U.S.

Environmental Protection Agency A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale ...

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, but may be porphyritic, containing larger mineral crystals ( phenocrysts) in an otherwise fine-grained groundmass. The miner ...

lava near

Durkee, Oregon Durkee is an unincorporated community in Baker County, Oregon, United States. It has a post office with the ZIP code of 97905. Durkee lies at the Vandercar Road exit of Interstate 84. Durkee is known as the site of Oregon's only cement plant ...

. 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 Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the ''adsorbate'' on the surface of the ''adsorbent''. This process differs from absorption, in which a ...

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; french: Centre International de Recherche sur le Cancer, CIRC) is an intergovernmental agency forming part of the World Health Organization of the United Nations. Its role is to conduct and ...

as a Group 1 Carcinogen. The prevalence of malignant

pleural The pleural cavity, pleural space, or interpleural space is the potential space between the pleurae of the pleural sac that surrounds each lung. A small amount of serous pleural fluid is maintained in the pleural cavity to enable lubrication b ...

and peritoneal mesothelioma due to erionite exposure in the

Cappadocia Cappadocia or Capadocia (; tr, Kapadokya), is a historical region in Central Anatolia, Turkey. It largely is in the provinces Nevşehir, Kayseri, Aksaray, Kırşehir, Sivas and Niğde. According to Herodotus, in the time of the Ionian Revo ...

region of

Central Anatolia The Central Anatolia Region ( tr, İç Anadolu Bölgesi) is a geographical region of Turkey. The largest city in the region is Ankara. Other big cities are Konya, Kayseri, Eskişehir, Sivas, and Aksaray. Located in Central Turkey, it is b ...

is very high. Descriptive studies have reported an excess of mortality from

mesothelioma Mesothelioma is a type of cancer that develops from the thin layer of tissue that covers many of the internal organs (known as the mesothelium). The most common area affected is the lining of the lungs and chest wall. Less commonly the lining ...

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 Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock ...

. There is sufficient evidence of carcinogenicity of erionite in

experimental animal Animal testing, also known as animal experimentation, animal research, and ''in vivo'' testing, is the use of non-human animals in experiments that seek to control the variables that affect the behavior or biological system under study. This ...

s. Rats exposed to erionite by inhalation or injection ( intrapleural or

intraperitoneal The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mesothel ...

) 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 high incidences of mesotheliomas. 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 ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

, and

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its ...

. 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 Sioux. North Dakota is bordered by the Canadian provinces of Saskatchewan and Manitoba to the north and by the U.S. states of Minnesota to the east, ...

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

lung cancer Lung cancer, also known as lung carcinoma (since about 98–99% of all lung cancers are carcinomas), is a malignant lung tumor characterized by uncontrolled cell growth in tissues of the lung. Lung carcinomas derive from transformed, mali ...

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

mesothelioma and other lung problems in the Turkish village of Tuzkoy near Nevsehir in the popular tourist region of

Cappadoccia Cappadocia or Capadocia (; tr, Kapadokya), is a historical region in Central Anatolia, Turkey. It largely is in the provinces Nevşehir, Kayseri, Aksaray, Kırşehir, Sivas and Niğde. According to Herodotus, in the time of the Ionian Revolt ...

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 (, ; vec, Vèneto ) or Venetia is one of the 20 regions of Italy. Its population is about five million, ranking fourth in Italy. The region's capital is Venice while the biggest city is Verona. Veneto was part of the Roman Empire unt ...

References

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

External links