Trüstedtit

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Trüstedtit
General and classification
chemical formula
  • Ni 2+ Ni 3+ 2 Se 4
  • Ni 3 Se 4
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.DA.05 ( 8th edition : II / D.01)
02.10.01.09
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  = 9.94  Å
Formula units Z  = 8
Physical Properties
Mohs hardness ≈2.5 to 3
Density (g / cm 3 ) calculated: 6.62
Cleavage not defined
colour brass yellow
Line color not defined
transparency opaque
shine Metallic luster

Trüstedtit is a very rarely occurring mineral from the mineral class of "sulfides and sulfosalts" with the chemical composition Ni 2+ Ni 3+ 2 Se 4 , also simpler Ni 3 Se 4 , and thus, chemically speaking, a nickel selenide with the molar ratio of nickel to selenium equal to 3: 4 and the nickel analog of Bornhardtite . Structurally, both belong to the group of spinels .

Trüstedtite crystallizes in the cubic crystal system , but has so far only been discovered under an ore microscope as inclusions of tiny, idiomorphic crystals in Clausthalite . The mineral is opaque and appears brass yellow with a metallic sheen under the incident light microscope .

With polydymite (Ni 2+ Ni 3+ 2 S 4 ), Trüstedtite forms mixed crystals , the color of which tends from yellow to olive with increasing sulfur content .

Etymology and history

Otto Trüstedt (1866–1929)

The synthetic compound Ni 3 Se 4 , albeit in monoclinic symmetry, was already presented in 1960 by Johannes-Erich Hiller and W. Wegener.

As a natural mineral formation, Trüstedtite was first discovered together with Kullerudit , Mäkinenite , Sederholmit and Wilkmanite in mineral samples from the Kitka Valley near Kuusamo in the Finnish landscape of Northern Ostrobothnia and described by Yrjö Vuorelainen , A. Huhma and TA Häkli. They named the mineral after the Finnish geologist and mining engineer Otto (Alexander Paul) Trüstedt (1866–1929) to honor his pioneering work in the development of prospecting methods that led to the discovery of the Outokumpu deposits.

After Trüstedtite was recognized as an independent mineral species by the International Mineralogical Association (IMA) with a vote of over 60%, the first description was published in 1964 in the scientific magazine Comptes Rendus de la Société Géologique de Finlande .

The type material ( Cotyp , CT) from Trüstedtit is kept at Mines ParisTech in Paris (France).

classification

The current classification of the IMA counts the Trüstedtite to the spinel supergroup , where together with Bornhardtite and Tyrrellite it forms the Bornhardtite subgroup within the Selenospinelle.

Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the Trüstedtite belonged to the mineral class of "sulfides and sulfosalts" and there to the department of "sulfides with [the molar ratio] metal: S, Se, Te <1: 1 "where he together with Bornhardtit, Cadmoindit , Carrollit , daubréelite , Fletcherit , Florensovit , greigite , Indit , Kalininit , linnaeite , Polydymit , Siegenit , Tyrrellit and Violarite the" linnaeite group "with the system number. II / D.01 formed.

In contrast , the 9th edition of Strunz's mineral systematics, which has been in force since 2001 and is used by the IMA, classifies Trüstedtite in the category of “metal sulfides with M: S = 3: 4 and 2: 3”. This is further subdivided according to the exact molar ratio, so that the mineral can be found according to its composition in the subsection "M: S = 3: 4", where it is found together with Bornhardtite, Cadmoindite, Carrollite, Cuproiridsite , Cuprorhodsite , Daubréelite, Ferrorhodsite , Fletcherit, Florensovit, greigite, Indit, Kalininit, linneite, Malanit , Polydymit, Siegenit, Tyrrellit, Violarite and Xingzhongit the "Linneitgruppe" system no. 2.DA.05 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Trüstedtite to the class of "sulfides and sulfosalts" and there in the department of "sulfide minerals". Here he is in the "Linneit group (isometric: Fd 3 m )" with the system no. 02.10.01 within the subsection " Sulphides - including selenides and tellurides - with the composition A m B n X p , with (m + n): p = 3: 4 ". Template: room group / 227

Chemism

The idealized, theoretical composition Ni 3 Se 4 requires 35.79% nickel (Ni) and 64.21% selenium (Se).

However, the analysis of the Finnish type material gave a slightly different composition of 29.5% nickel, 6.4% of cobalt and 64.1% of selenium and traces of copper and sulfur, with the empirical formula (Ni, Co) 3 Se 4 corresponds .

Crystal structure

Trüstedtite crystallizes isostructural, i.e. in the same structure type , with tyrrellite in the cubic crystal system in the space group Fd 3 m (space group no. 227) with the lattice parameter a  = 9.94  Å and 8 formula units per unit cell . Template: room group / 227

properties

The Mohs hardness of Trüstedtit was determined to be ≈ 2.5 to 3. Due to the insufficient amount of material, the density of the mineral could not be measured so far, but only calculated based on the crystal structure and amounts to 6.62 g / cm³.

The reflectivity of Trüstedtit is higher than that of Sederholmit and Penroseit. Trüstedtit has no internal reflections.

Modifications and varieties

The compound Ni 3 Se 4 is dimorphic and occurs naturally in addition to the cubic crystallizing Trüstedtite as monoclinic crystallizing Wilkmanite .

Education and Locations

At its type locality , the Kitka Valley in Finland, located Trüstedtit found in uranium-bearing calcite - transitions in Sill a shale formation consisting of albite - diabase . In addition to the accompanying minerals Clausthalit, Kullerudit, Mäkinenit, Sederholmit (also β-NiSe ) and Wilkmanit, Penroseit appeared among others .

In the Gold -Selen- deposit Qiongmo in circles Zoige (also Dzöge ) in the north of the Chinese province of Sichuan joined the mineral alongside native gold, you still associated with selenhaltigem Famatinit , Gersdorffit and stibnite and with Antimonselit , barite , quartz and Tiemannite on.

The only known site in Germany so far is the former mining area Tilkerode ( Abberode ) in the district of Mansfeld-Südharz in Saxony-Anhalt. In the numerous tunnels, pingen , heaps and small quarries, iron ore was primarily mined until 1865. From 1825 it was also recognized that the ores contained considerable gold and selenium contents.

Furthermore, only one small calcite dike known as Hope's Nose with gold and palladium mineralization near Torquay in the English county of Devon has been documented as a location for Trüstedtite (as of 2018).

See also

literature

  • Y. Vuorelainen, A. Huhma, A. Häkli: Sederholmite, wilkmanite, kullerudite, mäkinenite, and trüstedtite, five new nickel selenide minerals . In: Comptes Rendus de la Société Géologique de Finlande . tape 36 , 1964, pp. 113–125 (English, rruff.info [PDF; 635 kB ; accessed on October 1, 2018]).
  • Michael Fleischer : New mineral names . In: American Mineralogist . tape 50 , no. 3–4 , 1965, pp. 519–522 (English, minsocam.org [PDF; 314 kB ; accessed on October 1, 2018]).
  • Carl Hintze: Handbook of Mineralogy . Supplementary volume III. New minerals and new mineral names (with addenda, corrections and additions). Ed .: Karl F. Chudoba. De Gruyter, Berlin 1968, p. 330–331 ( limited preview in Google Book search).
  • 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. 101 .

Web links

Individual evidence

  1. ↑ a b c IMA / CNMNC List of Mineral Names; March 2018 (PDF 1.65 MB)
  2. ↑ 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.  93 (English).
  3. ↑ a b Webmineral - Trüstedtite (English)
  4. ↑ a b 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 .
  5. ↑ a b c Trüstedtite . 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 October 1, 2018]).
  6. ↑ Carl Hintze: Handbook of Mineralogy . Supplementary volume III. New minerals and new mineral names (with addenda, corrections and additions). Ed .: Karl F. Chudoba. De Gruyter, Berlin 1968, p. 330–331 ( limited preview in Google Book search).
  7. ^ A b Paul Ramdohr : The ore minerals and their adhesions . 4th, revised and expanded edition. Akademie-Verlag, Berlin 1975, p.  755 .
  8. ↑ Johannes-Erich Hiller, W. Wegener: Investigations in the system nickel-selenium . In: New Yearbook for Mineralogy, Treatises . tape 94 , 1960, pp. 1147-1159 .
  9. ↑ International Mineralogical Association: Commission on New Minerals and Mineral Names: [New Mineral Names] . In: Mineralogical Magazine . tape 36 , 1967, p. 131–136 (English, minersoc.org [PDF; 205 kB ; accessed on October 1, 2018]).
  10. ↑ Catalog of Type Mineral Specimens - T. (PDF 87 kB) In: docs.wixstatic.com. Commission on Museums (IMA), December 12, 2018, p. 14 , accessed August 29, 2019 .
  11. ↑ Cristian Biagioni, Marco Pasero: The systematics of the spinel-type minerals: An overview . In: American Mineralogist . tape 99 , no. 7 , 2014, p. 1254–1264 , doi : 10.2138 / am.2014.4816 (English, preliminary version online [PDF]).
  12. ^ 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.  85 (English).
  13. ↑ Mineralienatlas : The selenium ore deposits of Tilkerode in the Eastern Harz
  14. ↑ Find location list for Trüstedtite at the Mineralienatlas and at Mindat