Erionite

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Erionite
Erionite-161794.jpg
Broken, radial-rayed erionite aggregate (size: 3.5 mm) from Mount Nero, San Pietro, Montecchio Maggiore , Italy
General and classification
chemical formula see single minerals
Mineral class
(and possibly department)
Silicates and Germanates
System no. to Strunz
and to Dana
9.GD.20 ( 8th edition : VIII / J.26)
77.01.02.05 (Erionit-Na), 77.01.02.05a (-K) and 77.01.02.05b (-Ca)
Crystallographic Data
Crystal system hexagonal
Crystal class ; symbol dihexagonal-dipyramidal; 6 / m  2 / m  2 / m
Space group P 6 3 / mmc (No. 194)Template: room group / 194
Lattice parameters see crystal structure
Formula units Z  = 1
Physical Properties
Mohs hardness 3.5 to 4
Density (g / cm 3 ) measured: 2.08; calculated: 2.13
Cleavage Please complete!
Break ; Tenacity splintery, brittle
colour white, green, gray, orange
Line color White
transparency transparent to translucent
shine Silky gloss
Crystal optics
Refractive indices n ω  = 1.471
n ε  = 1.474
Birefringence δ = 0.003
Optical character uniaxial positive

Erionite is a collective name for the minerals recognized by the International Mineralogical Association (IMA) and the end members of a seamless mixed series, consisting of Erionite-Na , Erionite-K and Erionite-Ca . These rarely occurring minerals belong to the family of zeolites within the mineral class of " silicates and germanates " and crystallize in the hexagonal crystal system with the following chemical composition:

  • Erionite-Na : Na 10 [Al 10 Si 26 O 72 ] • 24.6H 2 O
  • Erionite-K : K 10 [Al 10 Si 26 O 72 ] • 32H 2 O
  • Erionite-Ca : Ca 5 [Al 10 Si 26 O 72 ] · 31H 2 O

Etymology and history

Was first discovered erionite in rhyolite - Tuff at Durkee in Baker County in the US state of Oregon described in 1898 by Arthur Starr Eakle, of the mineral because of its mostly wool-like appearance after the Greek word and ancient Greek ἔριον Erion / / designated for "wool".

In 1997, the "Commission for new minerals, mineral names and classification" (English: Commission on new Minerals, Nomenclature and Classification ) decided to redefine and rename many minerals of the zeolite family, which also includes erionite. According to Douglas S. Coombs et al. is no longer the erionite recognized as a mixed series, but its end members Erionit-Na (described in 1969 by Sheppard and Gude), Erionit-K (described in 1998 by Passasslia et al.) and Erionit-Ca (described in 1967 by Harada et al.). recognized as independent minerals.

Erionite became known as a carcinogen (cancer-promoting substance), which forms larger, near-surface deposits especially in the area around the Turkish village of Tuzköy , but also in other regions of Cappadocia , and is found there in the tuff rock used as building material . The cancer rate in these areas is above average due to the air pollution with the fine mineral fibers (sometimes up to 100 times higher), which is why the villages are to be abandoned and their inhabitants relocated.

classification

In the meantime outdated, but still in use 8th edition of the mineral classification by Strunz the erionite belonged to the mineral class of "silicates and Germanates" and there to the general ward of the " framework silicates (tectosilicates)" where they together with Bellbergit , chabasite (Ca) , Chabazite- (K) , Chabazite- (Na) , Chabazite- (Sr) , Gmelinite- (Ca) , Gmelinite- (K) , Gmelinite- (Na) , Levyn- (Ca) , Levyn- (Na) , Mazzite , Mazzit- (Na) , Offretit , Perlialith , Tschernichit and Willhendersonit formed the "zeolite group (subgroup cube zeolites)".

Since 2001, fixed by the International Mineralogical Association used (IMA) 9th edition of Strunz'schen systematic mineral also arranges the erionite in the class of "silicates and Germanates", but there into the already finely subdivided department of the " framework silicates (tectosilicates) with zeolitic H 2 O; Family of zeolites ”. However, this department is further subdivided according to the crystal structure, so that the erionites can be found in the subdivision “Zeolites with chains of five rings”, where they only form the unnamed group 9.GD.20 together with bellbergite .

The systematics of minerals according to Dana also assigns the erionites to the class of "silicates and germanates", but there in the department of "framework silicates: zeolite group". Here they are together with Chabazite-Ca, Chabazite-Na, Chabazite-K, Chabazite-Sr, Herschelite, Willhendersonite, Offretite, Gmelinit-Na, Gmelinit-Ca, Gmelinit-K, Faujasit-Na, Faujasit-Ca, Faujasite-Mg , Levyn-Ca, Levyn-Na and Tschortnerit in the group of "Chabazites and allied species" with the system no. 77.01.02 to be found within the sub-section of " Real Zeolites ".

Crystal structure

Crystallographic Data
mineral Lattice parameters
Erionite-Na a  = 13.21  Å and c  = 15.05 Å
Erionite-K a  = 13.23 Å ​​and c  = 15.07 Å
Erionite-Ca a  = 13.33 Å and c  = 15.09 Å

All minerals crystallize hexagonally in the space group P 6 3 / mmc (space group no. 194) with the lattice parameters shown here, which differ only slightly, as well as one formula unit per unit cell . Template: room group / 194

properties

Colorless, prismatic erionite crystals from Ajo Mountain, Pima County , Arizona, USA

Erionite mainly develops radial or fibrous, wool-like mineral aggregates , but rarely also prismatic crystals up to about 15 mm in length with a hexagonal habit . Adhesions with Offretit and Lévyn are also known . In fine-needle, fibrous aggregate form, erionite is white and translucent, occasionally discolored yellow with a silky sheen due to foreign admixtures . The crystals themselves are colorless, transparent and have a glass luster on their surfaces.

Even if the fine crystal needles and fibers look and feel like wool, they are still very sensitive to mechanical stress due to their brittleness . They can be quickly destroyed with a light touch. The asbestos-like fiber mineral, similar to asbestos , can lead to mesothelioma .

Education and Locations

Erionite, fused with offretite (cave filling consists of celadonite and montmorillonite)

Erionite form in volcanic rocks such as basalt or converted rhyolite - tuffs , but also by sedimentation of fallen in salt lakes, volcanic ash. Accompanying minerals include calcite , dolomite , montmorillonite , opal , quartz , celadonite and various zeolites .

So far (as of 2011), erionites have generally been detected at around 160 sites worldwide, including in Eastern Antarctica , Australia , Bulgaria , Denmark , Germany , France , Greece , Iceland , Italy , Japan , Canada , New Zealand , Austria , Poland , Russia , Spain , Czech Republic , Turkey , the United Kingdom (UK, Great Britain) and the United States of America (USA).

Minerals specifically identified as Erionite-Na were first detected ( type locality ) on Cady Mountain in San Bernardino County, USA , but were also found on Mount Nero near Montecchio Maggiore (San Pietro) in Italy, on the Japanese island of Iki , near Dunseverick in the far north of Northern Ireland's Antrim County and also in the USA on Mount Killdeer in Dunn County (North Dakota) and in the "Durkee Fire Opal Mine" in Baker County (Oregon) .

Minerals identified as Erionite-K were found primarily at Kamloops in Canada, Otago in New Zealand and in several regions of the US states of Arizona , Oregon and Washington , with Rome in Marion County (Oregon) being registered as a type locality.

Minerals identified as Erionit-Ca could be found at Ettringer Bellerberg , a volcano near Ettringen (Eifel) in Germany; near Yssingeaux in France; near Oristano in Sardinia as well as on Monte Fasolo ( Euganean Hills ) and on Mount Nero near Montecchio Maggiore in Italy; at Maze in Niigata Prefecture , Japan ; Ústí nad Labem in the Czech Republic; near Tuzköy in Turkey as well as in the US counties Dunn , Slope and Stark in North Dakota and in Tillamook County in Oregon.

See also

Web links

Commons : Erionite  - collection of images, videos and audio files

Individual evidence

  1. a b c d e f g Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p.  709 .
  2. a b c d Mindat - Erionite (English)
  3. Arthur S Eakle: ART. VI .-- Erionite, a new Zeolite . In: American Journal of Science , July 1898; 6, 31 ( PDF 879 kB, English )
  4. Douglas S. Coombs et al .: Recommended Nomenclature For Zeolite Minerals: Report of the Subcommitee on Zeolites of the International Mineralogical Association, Commission On New Minerals And Mineral Names In: The Canadian Mineralogist , Volume 35 (1997), p. 1571– 1606 ( PDF 339 kB )
  5. Geo aktuell - Beautiful Cappadocia - Dangerous Cappadocia
  6. Spiegel online - tumor accumulation forces mass relocation
  7. Focus.de - Rare cancer kills rock dwellers of the UNESCO World Heritage
  8. Alessandro F. Gualtieri, Nicola Bursi Gandolfi, Simone Pollastri, Kilian Pollok, Falko Langenhorst: Where is iron in erionite? A multidisciplinary study on fibrous erionite-Na from Jersey (Nevada, USA) . In: Scientific Reports . tape 6 , November 28, 2016, ISSN  2045-2322 , doi : 10.1038 / srep37981 , PMID 27892512 , PMC 5125093 (free full text).
  9. Mineralien-Lexikon - Erionit ( Memento of the original from January 28, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / www.wissen-im-netz.info
  10. ^ National Asbestos Profile Germany , 2nd edition. Dortmund: Federal Institute for Occupational Safety and Health 2020. Pages 78, (PDF, 2 MB), DOI: 10.21934 / baua: bericht20200427
  11. Mindat - Erionite-Na
  12. ^ Mindat - Erionite-K
  13. Mindat - Erionite-Ca