Isomerism

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Isomerism
General and classification
other names
  • Fengluanite
  • Guanglinite
  • IMA 1973-057
chemical formula Pd 11 Sb 2 As 2
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.AC.05 ( 8th edition : II / A.05)
02.16.02.01
Crystallographic Data
Crystal system cubic
Crystal class ; symbol cubic hexakisoctahedral; 4 / m  3  2 / m
Space group Fd 3 m (No. 227)Template: room group / 227
Lattice parameters a  = 12.28  Å
Formula units Z  = 8
Physical Properties
Mohs hardness 5.5 ( VHN 100 = 587–597, average 592)
Density (g / cm 3 ) calculated: 10.33
Cleavage Please complete!
colour pale yellow in reflected light
Line color Please complete!
transparency opaque
shine Metallic luster

Isomerite is a very rarely occurring mineral from the mineral class of "sulfides and sulfosalts" with the chemical composition Pd 11 Sb 2 As 2 and is therefore chemically an alloy-like sulfide made of palladium , antimony and arsenic .

Isomerite crystallizes in the cubic crystal system and forms grains up to 0.8 mm in size and pale yellow in color.

Etymology and history

The mineral was discovered in 1974 by AM Clark, AJ Criddle and EE Fejer in the Itabira type locality in the Brazilian state of Minas Gerais . They named the new mineral after the very similar mineral Mertieit-I , which in turn is named after the American geologist John Beaver Mertie Jr.

classification

Already in the outdated, but still in use 8th edition of the mineral classification according to Strunz , isomertieite belonged to the mineral class of "sulfides and sulfosalts" and there to the department of "alloys and alloy-like compounds", where together with arsenopalladinite , athenite , genenkinite , mertieite- I , Mertieit-II , Miessiit , Majakit , Menshikovit , Naldrettit , Palladoarsenid , Palladobismutoarsenid , Palladodymit , Polkanovite , Rhodarsenid , Stibiopalladinit , Stillwaterit , Ungavait and Vincentit the "Arsenopalladinit-Gruppe" with the system no. II / A.05 .

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns isomerism to the category of "alloys and alloy-like compounds". However, this is further subdivided according to the metals and semi-metals predominating in the compound, so that the mineral can be found according to its composition in the sub-section "Alloys of semi-metals with platinum group elements (PGE)", where it is only found together with miessiite forms the unnamed group 2.AC.15a .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the isomerism to the class of "sulfides and sulfosalts" and there in the department of "sulfide minerals". Here it can also be found together with Miessiit in the unnamed group 02.16.02 within the subsection " Sulphides - including selenides and tellurides - with various formulas ".

Modifications and varieties

The mineral is dimorphic to Mertieit-I.

Education and Locations

Isomerism is formed in heavy metal concentrates that have arisen from Precambrian iron and precious metal deposits. Depending on where it was found , it is associated with arsenopalladinite , palladite , athenite and hematite ; Chalcopyrite , millerite , kotulskite , arsenopalladinite and hematite or hongshiite , cooperite , sperrylite , vysotskite , magnetite , bornite , polydymite , diopside , actinolite and epidote .

Only a few sites are known of the very rare mineral. In addition to the type locality, Isomertieit was found in Curionópolis , in the Brazilian state of Pará , Lac-des-Îles in Ontario ( Canada ), Fengning in the Chinese province of Hebei , Lapland in Finland , Bleida in Morocco , Russia , the Bushveld complex in South Africa , Torquay and the island of Rum in the United Kingdom and the US states of Alaska and Minnesota .

Crystal structure

Isomertieite crystallizes in the cubic crystal system in the space group Fd 3 m (space group no. 227) with the lattice parameter a = 12.283  Å and eight formula units per unit cell . Template: room group / 227

See also

literature

  • AM Clark, AJ Criddle and EE Fejer: Palladium Arsenide-Antimonides from Itabira, Minas Gerais, Brazil . In: Mineralogical Magazine . tape 39 , 1974, p. 528-543 ( minersoc.org [PDF; 1,2 MB ; accessed on February 19, 2018]).
  • Michael Fleischer : New Mineral Names . In: American Mineralogist . tape 59 , 1974, pp. 1330-1332 ( minsocam.org [PDF; 337 kB ; accessed on February 19, 2018]).
  • Y. Vuorelainen, TA Haekli, E. Haenninen, Heikki Papunen, J. Reino, R. Toernroos: Isomertieite and other platinum-group minerals from the Konttijaervi layered mafic intrusion, northern Finland . In: Economic Geology . tape 77 , no. 6 , October 1, 1982, p. 1511-1518 , doi : 10.2113 / gsecongeo.77.6.1511 .
  • Pete J. Dunn, Louis J. Cabri, Andrew M. Clark, Michael Fleischer : New Mineral Names. New data . In: American Mineralogist . tape 68 , 1983, pp. 849–852 ( minsocam.org [PDF; 457 kB ; accessed on February 19, 2018]).

Web links

Individual evidence

  1. ^ A b Michael Fleischer , Louis J. Cabri, Adolf Pabst : New Mineral Names . In: American Mineralogist, Volume . tape  65 , 1980, pp. 406–408 ( minsocam.org [PDF; 377 kB ; accessed on February 19, 2018]).
  2. ^ IMA / CNMNC List of Mineral Names; November 2017 (PDF 1.67 MB)
  3. ^ 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.  60 .
  4. ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 6th completely revised and supplemented edition. Weise, Munich 2014, ISBN 978-3-921656-80-8 .
  5. ↑ a b c Isomertieite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 62  kB ; accessed on February 19, 2018]).