Irarsite

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Irarsite
General and classification
other names

IMA 1966-028

chemical formula
  • IrAsS
  • (Ir, Ru, Rh, Pt) AsS
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.EB.25 ( 8th edition : II / C.06c)
02.12.03.07
Crystallographic Data
Crystal system cubic
Crystal class ; symbol cubic-disdodecahedral; 2 / m  3
Space group Pa 3 (No. 205)Template: room group / 205
Lattice parameters a  = 5.78  Å
Formula units Z  = 4
Physical Properties
Mohs hardness 6.5 to 7 ( VHN = 976 kg / mm 2 )
Density (g / cm 3 ) calculated: 11.92
Cleavage not defined
Break ; Tenacity brittle
colour iron black, on polished surfaces gray-white with a bluish tinge
Line color not defined
transparency opaque (opaque)
shine Metallic luster

Irarsite is a relatively seldom occurring mineral from the mineral class of " sulphides and sulphosalts " with the idealized chemical composition IrAsS and thus chemically an iridium - arsenic- sulphide.

Irarsite crystallizes in the cubic crystal system and is usually found in the form of small grains up to about one millimeter in size or grown together with native platinum , ruthenium-containing hollingworthite and laurite as well as inclusions in chromite . The mineral, which is opaque in every form, shows a metallic sheen on the surfaces of the iron-black grains . Under the incident light microscope , polished surfaces show a gray-white reflection color with a bluish tinge.

Etymology and history

The synthetic compound IrAsS could already be represented in 1963 by F. Hullinger, who also determined the crystallographic data of the pure substance.

The compound was first discovered as a natural mineral formation in the Onverwacht platinum metal mine in the area of Mashishing ( Lydenburg until 2006 ) in the South African province of Mpumalanga . It was first described in 1966 by Alexandr Dimitrievich Genkin (1920–2010), NN Zhuravlev, NV Troneva and IV Muraveva (Russian: А. Д. Генкин, Н. Н. Журавлев, Н. В. Троунева, И. В. Мевав) the sulphide mineral in accordance with the composition of ( Ir Idium, Ars s) designated.

The type material of the mineral is said to have been deposited in the collection of the Mineralogical Museum of the Russian Academy of Sciences in Moscow . However , this is not documented in the type mineral catalog of the International Mineralogical Association (IMA), which was last updated in 2018 .

classification

Already in the outdated 8th edition of the mineral classification according to Strunz , the irarsite belonged to the mineral class of "sulfides and sulfosalts" and there to the department of "sulfides with [the substance ratio] M: S <1: 1", where together with hollingworthite it belonged to the " Hollingworthit series “with the system no. II / C.06c .

In the Lapis mineral directory according to Stefan Weiß, which, out of consideration for private collectors and institutional collections, is still based on this old form of Karl Hugo Strunz's system , the mineral was given the system and mineral number. II / D.18-60 . In the "Lapis Classification" This also corresponds to the department "sulfides with metal: S, Se, Te <1: 1" where Irarsit with Cobaltit , Gersdorffit , Hollingworthit, Jolliffeit , Kalungait , Milotait , Platarsit , Tolovkit , Ullmannit and Willyamit forms the "cobaltite group" (II / D.18) (as of 2018).

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and was updated by the IMA until 2009, classifies the irarsite in the newly defined section of “metal sulfides with a molar ratio of M: S ≤ 1: 2”. This is further subdivided according to the exact molar ratio and the predominant metals in the compound, so that the mineral can be found in the sub-section "M: S = 1: 2, with Fe, Co, Ni, PGE etc." according to its composition, where it together with Changchengit , cobaltite, Gersdorffit-P2 1 3 , Gersdorffit-Pa 3 , Gersdorffit-Pca2 1 , Hollingworthit, Jolliffeit, Kalungait, Krutovit , Maslovit , Mayingit , Michenerit , Milotait, Padmait , Platarsit, Testibiopalladit , Tolovkit, Ullmannit and Willyamit the "Gersdorffitgruppe" with the system no. 2.EB.25 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the irarsite to the class of "sulfides and sulfosalts" and there in the department of "sulfide minerals". Here it is in the " cobaltite group (cubic or pseudocubic crystals) " with the system no. 02.12.03 within the subsection "Sulphides - including selenides and tellurides - with the composition A m B n X p , with (m + n): p = 1: 2".

Chemism

According to the ideal (theoretical) composition of irarsite with the pure formula IrAsS, the mineral consists of iridium (Ir), arsenic (As) and sulfur (S) in a 1: 1: 1 ratio . This corresponds to a mass fraction (% by weight) of 64, 24% Ir, 25.04% As and 10.72% S.

The microprobe analysis of Irarsitproben from the close to the type locality Onverwacht mine located Driekop mine but showed different levels of 23.0% Ir, and 34.5% As, 11.6% S and an additional 12.6% platinum (Pt), 9 , 4% ruthenium (Ru) and 7.2% rhodium (Rh), which represent some of the original elements ( substitution , diadochy). This composition corresponds to the empirical formula (Ir 1.45 Ru 1.13 Rh 0.84 Pt 0.78 ) 4.2 As 5.6 S 4.4 , resulting in the mixed formula ( Ir, Ru, Rh, Pt) AsS simplified. The elements indicated in the round brackets can represent each other in the formula, but are always in the same proportion to the remaining components of the mineral.

Crystal structure

Irarsite crystallizes cubically in the pyrite structure in the space group Pa 3 (space group no. 205) with the lattice parameter a  = 5.78  Å and four formula units per unit cell . Template: room group / 205

properties

With a Mohs hardness of 6.5 to 7, which corresponds to a Vickers hardness (VH, English VHN) of 976 kg / mm 2 , irarsite is one of the hard minerals. It can no longer be scratched with a steel needle, but if it is of the appropriate size, it would be able to scratch window glass, similar to the reference mineral quartz (hardness 7) .

Due to the small sample size, the density of the mineral could not be measured. The density calculated from the crystal data is 11.92 g / cm 3 .

Education and Locations

Irarsite forms in hortonolite - dunites . In addition to native platinum , ruthenium-containing hollingworthite , laurite and chromite, depending on the location, chalcopyrite , chalcosine , cobaltite , gersdorffite , iridarsenite , magnetite , nickeline , olivine , pentlandite , pyrrhotite , ruthenarsenite , rutheniridosmin and sperrylite can occur as accompanying minerals .

As a rather rare mineral formation, irarsite can sometimes be abundant at various sites, but overall it is not very common. So far, around 170 locations have been documented (as of 2020). In addition to its type locality in the Onverwacht platinum metal mine , the mineral was also found in Mpumalanga in the Mooihoek Farm 255 KT with platinum- iron - magnesium unit, also located near Mashishing ( Lydenburg ) . Other well-known localities in South Africa , apart from the Bushveld Complex as one of the most important platinum group element - deposits even more precious metal mines and opencast mines in Limpopo as, among others, in Mokopane ( Potgietersrus ), some platinum mines in Brits and Rustenburg (District Bojanala Platinum ) in the North West Province and the copper - nickel -PGE deposit Insizwa near the "Waterfall- Gorge " at the Eastern Cape , and the gold fields of the Witwatersrand .

In Austria, Irarsit has so far only been able to be found near Wolfsbach in the municipality of Drosendorf-Zissersdorf in Lower Austria, in the abandoned mining tunnels and trenches of the ancient Gaiswand mine at Haidbachgraben near Felben in the municipality of Mittersill ( Felbertal ) in the Salzburger Land and near Kraubath an der Mur , can be discovered in an unnamed pit on Mitterberg and Sommergraben in the municipality of Sankt Stefan ob Leoben in Styria.

Other locations include Argentina, Ethiopia, Australia, Brazil, Bulgaria, China, the Dominican Republic, the Ivory Coast, Finland, France, Greece, India, Italy, Japan, Canada, Kazakhstan, Kenya, Cuba, Madagascar, Mexico, Mongolia, Myanmar, New Caledonia, Norway, Papua New Guinea, the Philippines, Russia, Sweden, Serbia, Sierra Leone, Zimbabwe, Slovakia, Spain, Tanzania, Turkey, Ukraine, the United Kingdom (UK) and the United States of America America (USA).

The only documented site of extraterrestrial origin is the meteorite Acfer 217 , which was found in 1991 in the Algerian part of the Sahara and in which, in addition to irarsite, erlichmanite , ilmenite , laurite , moncheit , pentlandite , sperrylite , spinel and troilite could be detected.

See also

literature

  • F. Hullinger: New Compounds with Cobaltite Structure . In: Nature . tape 198 , no. 4878 , 1963, pp. 382–383 , doi : 10.1038 / 198382b0 , bibcode : 1963Natur.198..382H (English).
  • А. Д. Генкин, Н. Н. Журавлев, Н. В. Тронева, И. В. Муравьева: Ирарсит - Новый Сульфоарсенид Иридия, Родия, Рутения и Платины . In: Zapiski Vsesoyuznogo Mineralogicheskogo Obshchestva . tape 95 , no. 6 , 1966, pp. 700–712 (Russian, rruff.info [PDF; 1.6 MB ; accessed on May 1, 2020] English translation: AD Genkin, NN Zhuravlev, NV Troneva, IV Muraveva: Irarsite, a new sulfoarsenide of iridium, ruthenium, and plantinum. ).
  • Mahmud Tarkian, Hazel Margaret Prichard: Irarsite-hollingworthite solid-solution series and other associated Ru-, Os-, Ir-, and Rh-bearing PGM's from the Shetland ophiolite complex . In: Mineralium Deposita . tape 22 , 1987, pp. 178-184 , doi : 10.1007 / BF00206607 , bibcode : 1987MinDe..22..178T (English).
  • Michael Fleischer : New mineral names . In: American Mineralogist . tape 52 , 1967, p. 1579–1589 (English, rruff.info [PDF; 800 kB ; accessed on May 1, 2020]).

Web links

Individual evidence

  1. ↑ a b c Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: March 2020. (PDF; 2.44 MB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, March 2020, accessed May 1, 2020 .
  2. ^ A b c 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.  105 (English).
  3. ↑ a b c Stefan Weiss: The large Lapis mineral directory. All minerals from A - Z and their properties. Status 03/2018 . 7th, completely revised and supplemented edition. Weise, Munich 2018, ISBN 978-3-921656-83-9 .
  4. ↑ a b c d e f g h Irarsite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 (English, handbookofmineralogy.org [PDF; 60  kB ; accessed on May 1, 2020]).
  5. ↑ F. Hullinger: New compounds with Cobaltite Structure . In: Nature . tape 198 , no. 4878 , 1963, pp. 382–383 , doi : 10.1038 / 198382b0 , bibcode : 1963Natur.198..382H (English).
  6. ↑ Louis J. Cabri: Alexandr Dimitrievich Genkin (1920-2010) . In: The Canadian Mineralogist . tape 48 , no. 5 , 2010, p. 1317 , doi : 10.3749 / canmin.48.5.1317 (English, available to download from researchgate.net [PDF; 443 kB ; accessed on May 1, 2020]).
  7. ^ Obituary for Aleksandr Dmitrievich Genkin (1919-2010). In: mindat.org. Hudson Institute of Mineralogy, accessed May 1, 2020 .
  8. ^ A b Michael Fleischer : New mineral names . In: American Mineralogist . tape  52 , 1967, p. 1579–1589 (English, rruff.info [PDF; 800 kB ; accessed on May 1, 2020]).
  9. ↑ Catalog of Type Mineral Specimens - I. (PDF 29 kB) In: docs.wixstatic.com. Commission on Museums (IMA), December 12, 2018, accessed August 29, 2019 .
  10. ↑ Ernest H. Nickel, Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF; 1.82 MB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed May 1, 2020 .
  11. ↑ А. Д. Генкин, Н. Н. Журавлев, Н. В. Тронева, И. В. Муравьева: Ирарсит - Новый Сульфоарсенид Иридия, Родия, Рутения и Платины . In: Zapiski Vsesoyuznogo Mineralogicheskogo Obshchestva . tape 95 , no. 6 , 1966, pp. 707 (Russian, rruff.info [PDF; 1.6 MB ; accessed on May 1, 2020] English translation: AD Genkin, NN Zhuravlev, NV Troneva, IV Muraveva: Irarsite, a new sulfoarsenide of iridium, ruthenium, and plantinum. ).
  12. ↑ Localities for Irarsite. In: mindat.org. Hudson Institute of Mineralogy, accessed May 1, 2020 .
  13. ↑ Find location list for Irarsite in the Mineralienatlas and Mindat , accessed on May 1, 2020.
  14. ^ Meteoritical Bulletin Database - Acfer 217. In: lpi.usra.edu. Meteoritical Bulletin , accessed May 2, 2020 .
  15. ↑ ACFER 217 meteorites, Tamanghasset Province, Algeria. In: mindat.org. Hudson Institute of Mineralogy, accessed May 2, 2020 .