White mountainite

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White mountainite
Weissbergite.jpg
White mountainite crystal from Lookout Pass, Little Valley , Tooele County , Utah, USA
General and classification
other names

IMA 1975-040

chemical formula TlSbS 2
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.HD.05
03.07.07.01
Crystallographic Data
Crystal system triclinic
Crystal class ; symbol triclinic pinacoidal; 1
Space group P 1 (No. 2)Template: room group / 2
Lattice parameters a  = 6.12  Å ; b  = 6.29 Å; c  = 11.84 Å,
α  = 101.3 °; β  = 98.44 °; γ  = 103.2 °
Formula units Z  = 4
Physical Properties
Mohs hardness 1.5
Density (g / cm 3 ) measured: 5.79; calculated: 6.1
Cleavage four different levels of cleavage: one perfect, two very good, one good
Break ; Tenacity brittle
colour steel gray
Line color dark gray
transparency opaque
shine Metallic luster

Weissbergite is a very rarely occurring mineral from the mineral class of "sulfides and sulfosalts" with the chemical composition TlSbS 2 , so it consists of thallium , antimony and sulfur with a cation / chalcogen ratio of 1: 1. Weissbergite is thus according to the nomenclature International Mineralogical Association (IMA) a binary sulfosalt .

Weissbergite crystallizes in the triclinic crystal system and is mostly found in the form of irregular grains up to about 0.5 millimeters in size, but occasionally also develops prismatic to tabular crystals with parallel striped surfaces along the longitudinal axis.

The mineral is in any form opaque ( opaque ) and points to the steel-gray in reflected light and creamy white appearing, surfaces of a metallic luster . Weissbergite leaves a dark gray line on the marking board .

Etymology and history

Weissbergite was discovered for the first time in a targeted search for an antimony analogue of Lorándite (TlAsS 2 ) in the " Carlin gold mine" near Elko in the US state of Nevada . It was first described in 1978 by Frank W. Dickson and Arthur S. Radtke, who named the mineral after the American geologist and mineralogist Byron G. Weissberg (* 1930) in order to honor his contributions to the geochemistry of epithermal hydrothermal processes.

The type material of the mineral is in the Epithermal Mineral Collection of the Geological Department of Stanford University at Palo Alto (California) and in the National Museum of Natural History in Washington, DC under the catalog no. 144274 kept.

classification

Since the Weissbergite was only recognized as an independent mineral in 1975 and this was only published in 1978, it is not yet included in the 8th edition of the Strunz mineral classification, which has been outdated since 1977 . Only 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 , was the mineral given the system and mineral number. II / E.13-60 . In the "Lapis system" this corresponds to the class of "sulfides and sulfosalts" and there the section "sulfosalts (S: As, Sb, Bi = x)", with groups E.10 to E.14 sulfosalts with predominantly thallium and / or mercury and x = 4.0 to 1.6. Together with Edenharterite , Grumiplucite , Hutchinsonite , Jentschit , Livingstonite , Lorándite , Richardsollyite , Simonite , Tvalchrelidzeit , Vaughanite and Vrbait, Weissbergite forms an independent but unnamed group (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, classifies the Weissbergite in the department of “Sulphosalts with SnS as a model”. This is further subdivided according to the predominant metals in the compound, so that the mineral according to its composition can be found in the sub-section "With thallium (Tl)", where it is only together with Lorándite the "Lorándite-Weissbergite group" with the System no. 2.HD.05 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Weissbergite to the class of "sulfides and sulfosalts" and there in the department of "sulfosalts". Here he is the only member of the unnamed group 07/03/07 within the subdivision “ Sulphosalts with the ratio z / y = 2 and the composition (A + ) i (A 2+ ) j [B y C z ], A = metals , B = semi-metals, C = non-metals ”.

Chemism

The idealized (theoretical) composition of Weissbergite (TlSbS 2 ) consists of a mass fraction (% by weight) of 52.37% thallium (Tl), 31.20% antimony (Sb) and 16.43% sulfur (S).

Microprobe analyzes on four grains of the mineral from the type locality "Carlin Goldmine" in Nevada showed an almost pure formula composition of 52.3 to 52.9 wt .-% Tl, 30.8 to 31.4 wt .-% Sb and 16, 3 to 16.5 wt% S.

Crystal structure

Weissbergite crystallizes triclinically in the space group P 1 (space group no. 2) with the lattice parameters a  = 6.12  Å ; b  = 6.29 Å; c  = 11.84 Å; α = 101.3 °; β = 98.44 ° and γ = 103.2 ° as well as 4 formula units per unit cell . Template: room group / 2

Education and Locations

Weissbergite is formed by hydrothermal processes in silicified breccias from dolomitic carbonate rocks , where it usually occurs in association with stibnite and quartz .

In addition to its “Carlin gold mine” type locality, the mineral has so far only been found in a thallium prospect in the United States at Lookout Pass near Little Valley in Tooele County of Utah.

Other previously known sites are the gold-arsenic-antimony-thallium deposit Allchar in the south of North Macedonia and the Khokhoy gold field on the Khokhoy river of the same name, a right tributary of the Amga in the Sakha Republic, which belongs to the Russian Federation (as of 2020).

Another published site was the "Lengenbach" mine in the Binn valley in the Swiss canton of Valais , which was said to contain arsenic-rich white mountainite. Dan Topa, Stefan Graeser, Berthold Stoeger, Thomas Raber and Chris Stanley found neither arsenic-free nor arsenic-poor white mountainite in this pit in 2019. Instead, they discovered a new mineral having a composition of Tl 4 (Sb 4-x As x ) S 8 (with 1 <x <2) that they Drechslerit called.

See also

literature

  • Frank W. Dickson and Arthur S. Radtke: Weissbergite, TlSbS 2 , a new mineral from the Carlin gold deposit, Nevada . In: American Mineralogist . tape 63 , 1978, pp. 720–724 (English, rruff.info [PDF; 550 kB ; accessed on August 1, 2020]).
  • N. Rey, JC Jumas, J. Olivier-Fourcade, E. Philippot: Sur les composés III-V-VI: Etude structurale du disulfure d'antimoine et de thallium, TlSbS2 . In: Acta Crystallographica . C39, 1983, pp. 971-974 , doi : 10.1107 / S0108270183007040 (French).
  • T. Balić-Žunić, E. Makovicky, Y. Moëlo: Contributions to the crystal chemistry of thallium sulphosalts III. The crystal structure of lorandite (TlAsS 2 ) and its relation to weissbergite (TlSbS 2 ) . In: New Yearbook for Mineralogy, Treatises . tape 168 , 1995, pp. 213-235 (English).

Web links

Individual evidence

  1. ↑ 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 August 1, 2020 .
  2. ↑ a b c d e 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.  136 (English).
  3. ↑ a b Weissbergite . 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 August 1, 2020]).
  4. ↑ Weissbergite. In: mindat.org. Hudson Institute of Mineralogy, accessed August 1, 2020 .
  5. ↑ Yves Moëlo, Emil Makovicky, Nadejda N. Mozgova, John L. Jambor, Nigel Cook, Allan Pring, Werner Paar, Ernest H. Nickel, Stephan Graeser, Sven Karup-Møller, Tonči Balic-Žunic, William G. Mumme, Filippo Vurro, Dan Topa, Luca Bindi, Klaus Bente, Masaaki Shimizu: Sulfosalt systematics: a review. Report of the sulfosalt sub-committee of the IMA Commission on Ore Mineralogy . In: European Journal of Mineralogy . tape 20 , no. 1 , 2008, p. 7–46 , doi : 10.1127 / 0935-1221 / 2008 / 0020-1778 (English, rruff.info [PDF; 485 kB ; accessed on August 3, 2020]).
  6. ↑ 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 .
  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 2, 2020 .
  8. ↑ Weissbergite. In: Mineralienatlas Lexikon. Stefan Schorn u. a., accessed on August 2, 2020 .
  9. ^ Frank W. Dickson and Arthur S. Radtke: Weissbergite, TlSbS 2 , a new mineral from the Carlin gold deposit, Nevada . In: American Mineralogist . tape 63 , 1978, pp. 722 (English, rruff.info [PDF; 550 kB ; accessed on August 1, 2020]).
  10. ↑ Find location list for Weissbergite in the Mineralienatlas and Mindat , accessed on August 1, 2020.
  11. ^ Weissbergite from Lengenbach Quarry, Fäld, Binn, Goms, Valais, Switzerland. In: mindat.org. Hudson Institute of Mineralogy, accessed August 1, 2020 .
  12. ↑ Ritsuro Miyawaki, Frédéric Hatert, Marco Pasero, Stuart J. Mills: IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) Newsletter 52. New minerals and nomenclature modifications approved in 2019 . In: Mineralogical Magazine . tape 83 , 2019, pp. 887–893 , doi : 10.1180 / mgm.2019.73 (English, rruff.info [PDF; 182 kB ; accessed on August 3, 2020]).