Langisit

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Langisit
General and classification
other names

IMA 1968-023

chemical formula
  • CoAs
  • (Co 0.8 Ni 0.2 ) As
Mineral class
(and possibly department) 		Sulfides and sulfosalts (including selenides, tellurides, arsenides, antimonides, bismuthides, sulfarsenites, sulfantimonites, sulfbismuthites)
System no. to Strunz
and to Dana 		02.CC.05 ( 8th edition : II / B.09a)
02.08.11.09
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 a  = 3.54  Å ; c  = 5.13 Å
Formula units Z  = 2
Physical Properties
Mohs hardness 6 to 6.5 ( VHN 50 = 780–857)
Density (g / cm 3 ) calculated: 8.174
Cleavage not defined
colour reddish gray, leather-like yellow-brown with a pink tinge in incident light
Line color not defined
transparency opaque (opaque)
shine Metallic luster

Langisite is a very rarely occurring mineral from the mineral class of " sulfides and sulfosalts " with the idealized chemical composition CoAs and thus, chemically speaking, a cobalt arsenide, more precisely cobalt (III) arsenide . As close relatives of the sulfides, the arsenides are placed in the same class.

Langisite is the nickel analogue of nickel and crystallizes like this in the hexagonal crystal system , but could only be found in safflorite under an ore microscope in the form of irregular grains and lamellae . The mineral is opaque in any form ( opaque ), appears in the reflected-light microscope leather-like yellowish brown (English buff ) with a pink stitch and displays on the grain surfaces a metallic luster .

Etymology and history

Langisite was first discovered in the Langis silver mine ( 47 ° 45 ′  N , 80 ° 15 ′  W ) near Casey in the Canadian state of Ontario . The first description was made in 1969 by W. Petruk, DC Harris and JM Stewart after recognition by the International Mineralogical Association (internal entry number of the IMA 1968-023).

The type material of the mineral is listed in Ottawa in the Mineralogical Collection of the Geological Survey of Canada (GSC) under catalog no. 12140/1 (holotype) and in the "Canada Center for Mineral and Energy Technology" (CANMET) under catalog no. 329 (holotype) and in Toronto in the Royal Ontario Museum (ROM) under catalog no. M28883 / 4 kept.

classification

Already in the outdated 8th edition of the mineral classification according to Strunz , the langisite belonged to the mineral class of "sulfides and sulfosalts" and there to the division of "sulfides with [the molar ratio ] M (metal): S (sulfur) r = 1: 1", where he together with Achávalit (Achavalit) Breithauptit , Freboldit , Imgreit (discredited) Jaipurit , Kotulskit , Nickelin , pyrrhotite , Sederholmit , Smythit and troilite the "NiAs-series" with the system number. II / B.09a .

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 / C.20-10 . In the "Lapis system" this corresponds to the section "Sulphides with [the molar ratio] metal: S, Se, Te ≈ 1: 1", where Langisite together with Breithauptite, Freboldite, Hexatestibiopanickelite , Kotulskite, Nickelin, Sederholmit, Sorosit , Stumpflit , Sudburyit and Vavřínit and in the notes to Cherepanovit , polarity , Ruthenarsenit , Sobolevskit and Wassonit the "Nickelin group" is (as of 2018).

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and was last updated by the IMA in 2009, also classifies the langisite in the category of "Metal sulfides, M: S = 1: 1 (and similar)". However, this is further subdivided according to the predominant metals in the compound, so that the mineral can be found according to its composition in the sub-section "with nickel (Ni), iron (Fe), cobalt (Co) etc.", where it can be found together with Achávalit , Breithauptit, Hexatestibiopanickelit , Jaipurit , Kotulskit , Nickelin, Freboldit, Sederholmit, Sobolevskit, Stumpflit , Sudburyit , Vavřínit and Zlatogorit the "nickelin group" with the system no. 2.CC.05 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the langisite to the class of "sulphides and sulphosalts" and there in the category of "sulphide minerals". Here it is in the " Nickelin group (hexagonal: P6 3 / mmc) " with the system no. 08/02/11 within the subsection of "Sulphides - including selenides and tellurides - with the composition A m B n X p , with (m + n): p = 1: 1".

Chemism

According to the ideal (theoretical) chemical composition of langisite (CoAs), the mineral consists of cobalt (Co) and arsenic (As) in a molar ratio of 1: 1. This corresponds to a mass fraction of 44.03% by weight of Co and 55.97 Wt% As.

The microprobe analysis of the type material from the Langis mine, however, showed a slightly different composition of 35.5% by weight Co and 56.0% by weight As and also a content of 7.0% by weight nickel (Ni), which represents part of the cobalt (substitution, diadochie). The analysis values ​​correspond to the empirical formula (Co 0.84 Ni 0.16 ) Σ = 1.00 As 1.04 . Langisite therefore corresponds to the cobalt end member of the mixed crystal series NiAs - Co 0.8 Ni 0.2 As 1.0 and is thus the cobalt analogue of Nickelin.

Crystal structure

Langisite crystallizes isotypically with nickel in the hexagonal crystal system in the space group P 6 3 / mmc (space group no. 194) with the lattice parameters a  = 3.54  Å and c  = 5.13 Å and two formula units per unit cell . Template: room group / 194

Modifications and varieties

The compound cobalt (III) arsenide (Co) is dimorphic and occurs naturally as orthorhombically crystallizing modderite in addition to the hexagonally crystallizing langisite .

Education and Locations

Langisite forms in pockets of massive sulfide concentrates, mineralized fault grooves, and breccias cemented with calcite and quartz . Cobalt- containing bravoite , marcasite , maucherite , parkerite , pentlandite , pyrite , safflorite and siegenite can occur as accompanying minerals .

Its type locality , the silver mine Langis near the township of Casey, and also belongs to the province of Ontario Cobalterz - deposits in the region Cobalt - Gowganda are the only previous discovery sites for Langisit in Canada. In addition, the mineral could only be discovered in the uranium deposits in the north Bohemian region of Liberec in the Czech Republic, in Apigania Bay on the island of Tinos in Greece and in Littleham Bay near Budleigh Salterton in the English county of Devon (as of 2020).

See also

literature

  • W. Petruk, DC Harris, JM Stewart: Langisite, a new mineral, and the rare minerals cobalt pentlandite, siegenite, parkerite and bravoite from the Langis mine, Cobalt-Gowganda area, Ontario . In: The Canadian Mineralogist . tape 9 , 1969, p. 597–616 (English, rruff.info [PDF; 2,3 MB ; accessed on August 14, 2020]).
  • Michael Fleischer : New mineral names . In: American Mineralogist . tape 57 , 1972, p. 1909–1914 (English, rruff.info [PDF; 439 kB ; accessed on August 14, 2020]).

Web links

Individual evidence

  1. ↑ a b c d Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: July 2020. (PDF; 2.44 MB) In: cnmnc.main.jp . IMA / CNMNC, Marco Pasero, July 2020, accessed on August 14, 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.  85 (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 Langisite . 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; 58  kB ; accessed on August 14, 2020]).
  5. ^ László Horváth: Mineral Species discovered in Canada and species named after Canadians (The Canadian Mineralogist Special Publication 6) . 1st edition. Mineralogical Association of Canada, Ottawa 2003, ISBN 0-921294-40-9 , pp. 107 .
  6. ↑ Catalog of Type Mineral Specimens - L. (PDF 70 kB) In: docs.wixstatic.com. Commission on Museums (IMA), December 12, 2018, accessed August 14, 2020 .
  7. ↑ 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 August 14, 2020 .
  8. ↑ W. Petruk, DC Harris, JM Stewart: Langisite, a new mineral, and the rare minerals cobalt pentlandite, siegenite, parkerite and bravoite from the Langis mine, Cobalt-Gowganda area, Ontario . In: The Canadian Mineralogist . tape 9 , 1969, p. 601 (English, rruff.info [PDF; 2,3 MB ; accessed on August 14, 2020]).
  9. ^ Friedrich Klockmann : Klockmanns textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp.  447 (first edition: 1891).
  10. ↑ List of localities for langisite in the Mineralienatlas and Mindat , accessed on August 14, 2020.