Laurite

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Laurite
General and classification
chemical formula RuS 2
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.EB.05a ( 8th edition : II / C.05)
02.12.01.10
Similar minerals Hollingworthite , irarsite , sperrylite
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  = 5.61  Å
Formula units Z  = 4
Physical Properties
Mohs hardness 7.5 ( VHN 25 = 2760–2898 kg / mm 2 , average 2870)
Density (g / cm 3 ) measured: 6.43; calculated: 6.39
Cleavage completely after {111}
Break ; Tenacity slightly mussel-like; very brittle
colour iron black; white, gray or bluish on polished surfaces
Line color dark gray
transparency opaque (opaque)
shine Metallic luster

Laurite is a rather seldom occurring mineral from the mineral class of " sulphides and sulphosalts " with the idealized chemical composition RuS 2 and thus, chemically speaking, ruthenium disulphide .

Laurit crystallizes in the cubic crystal system and developed to a millimeter crystals , but is also found in the form of rounded grains and inclusions in other minerals. The mineral is in any form opaque ( opaque ) and displays on the surfaces of the iron-black crystals have a metallic luster . Polished surfaces can also appear white, gray or bluish under the reflected light microscope . In contrast, the line color of Laurit is dark gray.

Etymology and history

Waitz collected some platinum ore samples from a soap deposit on the part of the island of Borneo , which is now part of Indonesia , which were first analyzed by Böcking in 1855, although the new mineral was not yet noticed. Another chemical analysis carried out by Friedrich Wöhler finally brought the result that some of the iron-black grains and spheres were a previously unknown ruthenium sulfide with a low but clearly detectable content of osmium . The crystallographic properties of laurite were carried out by Wolfgang Sartorius von Waltershausen in Göttingen . The results of the research by Wöhler and Waltershausen were published in 1866 in the news of the Royal Society of Sciences and the Georg August University .

As a close friend of the American chemist Charles Arad Joy , Wöhler chose the name Laurit as a personal compliment to his wife Laura.

According to John Bowles, D. Atkin JLM Lambert, T. Deans and R. Phillips, who investigated the chemistry, reflection properties and sizes of the unit cell of the mixed crystal series of Erlichmanite (OsS 2 ) and Laurite in 1983, the exact type locality for laurite is a soap deposit on River Pontijn in the reign of Tanah Laut on Borneo.

The type material of the mineral is in the mineralogical collections of the Mineralogical-Petrographical Institute of the University of Göttingen under the collection no. 24541 kept.

classification

Already in the outdated 8th edition of the mineral classification according to Strunz , the laurite belonged to the mineral class of "sulfides and sulfosalts" and there to the department of "sulfides with M: S <1: 1", where it together with Aurostibit , Cattierit , Geversit , Hauerit , Michenerite , penroseit , pyrite , sperrylite , trogtalite , vaesite and villamanínite the "pyrite series" with the system no. II / C.05 formed.

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.17-100 . In the "Lapis system" this also corresponds to the section "Sulphides with metal: S, Se, Te <1: 1", where Laurite together with Aurostibite, Cattierite, Changchengite , Dzharkenite , Erlichmanite , Fukuchilit , Geversit, Hauerite, Insizwait , Krutaite , Maslovit , Mayingit , Michenerit, Padmait , Penroseite, pyrite, Sperrylith, Trogtalit, Testibiopalladit , Vaesit and Villamanínit the "pyrite group" formed (as 2018).

The 9th edition of Strunz's mineral systematics, which has been valid since 2001 and updated by the International Mineralogical Association (IMA) until 2009, classifies laurite in the more general section of “Metal sulfides with M: S ≤ 1: 2”. However, 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 Aurostibit, cattierite, Dzharkenit, Erlichmanit, Fukuchilit, Gaotaiit , Geversit, Hauerit, Insizwait, Iridisit , Krutaite, Penroseite, pyrite, Sperrylith, Trogtalit, Vaesit and Villamanínit the "pyrite group" with the system no. 2.EB.05a forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns laurite to the class of "sulfides and sulfosalts" and there in the department of "sulfide minerals". Here it is also in the "pyrite group (isometric: Pa 3 )" with the system no. 02.12.01 to be found within the subsection “ Sulphides - including selenides and tellurides - with the composition A m B n X p , with (m + n): p = 1: 2 ”. Template: room group / 205

Chemism

The idealized (theoretical) composition of laurite (RuS 2 ) consists of 61.18% ruthenium (Ru) and 38.82% sulfur (S). In the first analysis of the type material from Borneo, however, Wöhler was able to detect a significant proportion of osmium of 3.03%, with a Ru content of 65.18% and an S content of 31.79%.

In other laurite finds from Goodnews Bay in the Bethel Census Area of Alaska (USA), there were extraneous additions of iridium and from a soap deposit on the Río Pilpe , a tributary of the Río Guapi in the municipality of the same name in the Colombian department of Cauca, in addition to 12.7% osmium 5.3% iridium and 0.1% copper (Cu) can be detected.

Laurite forms a mixed crystal series with the osmium analogue Erlichmanite , which can be the reason for the often significant contents of osmium in the compound.

Crystal structure

Laurite crystallizes cubically in the pyrite structure in the space group Pa 3 (space group no. 205) with the lattice parameter a = 5.61  Å and four formula units per unit cell . Template: room group / 205

properties

With a Mohs hardness of 7.5, which corresponds to a Vickers hardness (VH, English VHN) of 2760 to 2898 kg / mm 2 with a test force of 25 grams (on average 2870 kg / mm 2 ), Laurite lies between the reference minerals quartz (hardness 7 ) and topaz (hardness 8) and would be able to scratch window glass with the appropriate size . The measured density of laurite is 6.43 g / cm 3 . The density calculated from the crystal data is slightly lower at 6.39 g / cm 3 .

The mineral reacts very brittle to mechanical stress and breaks like glass with weakly shell-shaped fracture surfaces. In addition, perfect cleavage according to the {111} octahedron was observed.

Laurite is infusible in front of the soldering tube, but crackles as violently as galena and initially develops a strong odor of sulphurous acid , which after a while changes to the odor of osmic acid .

Laurite is very resistant to acids and is not even attacked by aqua regia .

Education and Locations

Laurite forms in ultramafic complexes, but is mainly found in soaps containing platinum . Braggite , chromite , cooperite , sperrylite and other platinum metal minerals appear as accompanying minerals .

As a rather rare mineral formation, laurite can sometimes be abundant at different sites, but overall it is not very common. So far, around 240 locations for Laurite have been documented worldwide (as of 2020). Except at its type locality , the mineral in the Pontijn in the regency of Tanah According to found Indonesia still at a gold - prospecting on the holy mountain Meratus and in a heavy mineral soap riverside Tambiano in Borneo and to an unspecified reference to Sulawesi .

Other well-known soap deposits are located on the Tulameen River in the Canadian province of British Columbia, on the Yuba River near Hammonton in Yuba and Nevada Counties and on the Trinity River in the county of the same name near Douglas City in California. In addition, laurite is also from alluvial deposits such as the ophiolites on the Pirogues River in the southern province of New Caledonia and the Maud Creek on the Howard River in the Tasman District of the South Island of New Zealand.

In the Merensky Reef and the underlying Merensky Horizon in the Bushveld Complex of the Transvaal province of South Africa , a multi-layered area of igneous rock and the world's largest known reserves of platinum metals , laurite occurs as the local predominant mineral. In addition, idiomorphic laurite crystals were observed in the Onverwacht Pipe, which is also located in the Bushveld complex. Also known for its high productivity of platinum metals - including laurite - is the Kondjor massif (English Konder or Kondyor ) in the Aldan highlands of the Russian Republic of Sakha (Yakutia).

In Austria, Laurit could so far only be discovered near Wolfsbach in the municipality of Drosendorf-Zissersdorf in Lower Austria and near Kraubath an der Mur , in an unnamed pit on Mitterberg and on Sommergraben in the municipality of Sankt Stefan ob Leoben in Styria. Locations in Germany and Switzerland are not yet known.

Other sites are in Albania, Algeria, Ethiopia, Australia, Brazil, Bulgaria, China, Costa Rica, the Dominican Republic, Ecuador, the Ivory Coast, Finland, France, Greece, India, Iraq, Italy, Japan, Canada, Kazakhstan, Cuba, Madagascar, Morocco, Mexico, Mongolia, Myanmar, New Zealand, North Macedonia, Norway, Oman, East Timor, Papua New Guinea, the Philippines, Sierra Leone, Zimbabwe, Slovakia, Spain, Tanzania, Turkey, Ukraine, in the United Kingdom (here: Scotland), other states in the USA and Cyprus.

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 laurite, erlichmanite, ilmenite , irarsite , moncheit , pentlandite , sperrylite, spinel and troilite could be detected.

See also

literature

  • F. Wöhler: About a new mineral from Bornéo . In: News from the Royal Society of Sciences and the Georg August University . tape 12 . Verlag der Dieterichschen Buchhandlung, Göttingen 1866, p. 155–160 ( rruff.info [PDF; 263 kB ; accessed on April 6, 2020]).
  • Sartorius von Waltershausen: About the crystal forms and mineralogical peculiarities of Llaurite . In: News from the Royal Society of Scientists and the Georg August University . tape 12 , 1866, pp. 160–163 ( rruff.info [PDF; 367 kB ; accessed on April 6, 2020]).
  • BF Leonard, George A. Desborough: Ore microscopy and chemical composition of some laurites . In: American Mineralogist . 54 date = 1969, p. 1330–1346 (English, rruff.info [PDF; 1.3 MB ; accessed on April 7, 2020]).

Web links

Individual evidence

  1. ↑ a b c d 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.  104 (English).
  2. ↑ Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: March 2020. (PDF; 1729 kB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, March 2020, accessed April 6, 2020 .
  3. ^ A b Paul Ramdohr : The ore minerals and their adhesions . 4th, revised and expanded edition. Akademie-Verlag, Berlin 1975, p.  879 .
  4. ↑ a b David Barthelmy: Hauerite Mineral Data. In: webmineral.com. Retrieved April 6, 2020 .
  5. ↑ a b c d e f g h i j Laurite . 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; 63  kB ; accessed on April 6, 2020]).
  6. ↑ a b c Laurite. In: mindat.org. Hudson Institute of Mineralogy, accessed April 6, 2020 .
  7. ↑ a b c Sartorius von Waltershausen: About the crystal forms and mineralogical peculiarities of Llaurite . In: News from the Royal Society of Scientists and the Georg August University . tape 12 , 1866, pp. 160–163 ( rruff.info [PDF; 367 kB ; accessed on April 6, 2020]).
  8. ↑ a b c d F. Wöhler: About a new mineral from Bornéo . In: News from the Royal Society of Sciences and the Georg August University . tape 12 . Verlag der Dieterichschen Buchhandlung, Göttingen 1866, p. 155–160 ( rruff.info [PDF; 263 kB ; accessed on April 6, 2020]).
  9. ↑ John FW Bowles, D. Atkin JLM Lambert, T. Deans and R. Phillips: The chemistry, reflectance, and cell size of the erlichmanite (OsS 2 ) -laurite (RuS 2 ) series . In: Mineralogical Magazine . tape 47 , no. 345 , 1983, pp. 465–471 , doi : 10.1180 / minmag.1983.047.345.07 (English, available online at researchgate.net [accessed April 6, 2020]).
  10. ↑ Catalog of Type Mineral Specimens - L. (PDF 70 kB) In: docs.wixstatic.com. Commission on Museums (IMA), December 12, 2018, accessed August 29, 2019 .
  11. ↑ 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 .
  12. ↑ Ernest H. Nickel, Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF; 1816 kB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed April 6, 2020 .
  13. ↑ Localities for Laurite. In: mindat.org. Hudson Institute of Mineralogy, accessed April 6, 2020 .
  14. ↑ Richard V. Gaines, H. Catherine W. Skinner, Eugene E. Foord, Brian Mason , Abraham Rosenzweig: Dana's New Mineralogy . 8th edition. John Wiley & Sons, New York et al. 1997, ISBN 0-471-19310-0 , pp. 117 .
  15. ^ Helmut Schrätze , Karl-Ludwig Weiner : Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp.  252 .
  16. ↑ List of locations for laurite in the Mineralienatlas and Mindat , accessed on April 6, 2020.
  17. ^ Meteoritical Bulletin Database - Acfer 217. In: lpi.usra.edu. Meteoritical Bulletin , accessed April 7, 2020 .
  18. ↑ ACFER 217 meteorites, Tamanghasset Province, Algeria. In: mindat.org. Hudson Institute of Mineralogy, accessed April 6, 2020 .