Xanthocone

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Xanthocone
Xanthoconite-220973.jpg
"Strip-shaped" xanthocone crystal from the "Imiter Mine", Boumalne-Dadès, Ouarzazate Province, Morocco (image size: 1 mm)
General and classification
other names
  • Xanthoconite
  • Xanthoconite
  • Rittingerit
chemical formula Ag 3 AsS 3
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.GA.10 ( 8th edition : II / E.07)
04/03/02/01
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic 2 / m
Room group (no.) C 2 / c (No. 15)
Lattice parameters a  = 12.00  Å ; b  = 6.26 Å; c  = 17.08 Å
β  = 110.0 °
Formula units Z  = 8
Twinning pseudoorthorhombic twins according to {001}
Physical Properties
Mohs hardness 2 to 3
Density (g / cm 3 ) measured: 5.54 (14); calculated: 5.53
Cleavage clearly after {001}
Break ; Tenacity shell-like
colour dark carmine red to clove brown , in thin crystals of bitter orange yellow
Line color yellow
transparency translucent to opaque
shine Diamond luster
Crystal optics
Optical character biaxial negative
Axis angle 2V = 34 °

Xanthocone is a rarely occurring mineral from the mineral class of " sulfides and sulfosalts ". It crystallizes in the monoclinic crystal system with the composition Ag 3 AsS 3 , so it is chemically a silver - arsenic sulfide.

Xanthocon usually develops tabular, strip-shaped crystals of bitter orange- yellow color, but also grape-like, kidney-shaped or radial mineral aggregates from dark carmine-red to clove-brown color. Xanthocon leaves a characteristic yellow line on the marking board .

Special properties

Already August Breithaupt and GP Plattner presented in the analysis of the material firmly that "the mineral is so light liquid that it already melts in the flame of a candle in evolution of vapors that smell of sulfuric acid and of arsenic." In fact, similar to the closely related Proustite , xanthocone is easy to melt in front of the soldering tube , whereby sulphurous acid and arsenic vapors with a characteristic odor are deposited.

Etymology and history

Xanthokon was first discovered in 1797 in the “Himmelsfürst mine” near Brand-Erbisdorf (Saxony) in Germany and described in 1840 by Breithaupt, who named the mineral because of its characteristic line color after the Greek words ξανθς “xanthos” for yellow and χόνις “konis” for powder named.

classification

In the meantime outdated, but still in use 8th edition of the mineral classification by Strunz of Xanthokon belonged to the mineral class of "sulfides and sulfosalts" and there to the general ward of the "thio" where he along with Proustite, Pyrargyrite , Pyrostilpnit , Quadratit and Samsonit the unnamed group II / E.07 formed.

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 the xanthocone to the class of “sulfides and sulfosalts”, but in the newly defined section of “sulfoarsenides, sulfoantimonides, sulfobismuthides” " a. This department is further subdivided according to the crystal structure and the possible presence of further sulfur, so that the mineral according to its structure and its composition in the subdivision of "island sulfarsenides (Neso sulfarsenides) etc., without additional sulfur (S)" can be found where it only forms the unnamed group 2.GA.10 together with pyrostilpnite .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , sorts the xanthocone into the class of "sulfides and sulfosalts" and there in the department of "sulfosalts". Here he is the namesake of the "Xanthokongruppe" with the system no. 03.04.02 and the other member Pyrostilpnit within the subsection " Sulphosalts with the ratio 3> z / y and the composition (A + ) i (A 2+ ) j [B y C z ], A = metals, B = semi-metals, C = non-metals ”.

Modifications and varieties

Xanthokon is adjacent to the Proustit the second modification of the compound Ag 3 AsS 3 .

Education and Locations

Xanthocone is formed by hydrothermal processes in ore veins containing silver and arsenic , where it occurs in paragenesis mainly with Proustite, but also with pyrargyrite , acanthite , calcite and native arsenic .

So far (as of 2009) the mineral has been found at around 70 sites around the world, including Chañarcillo in the Chilean Región de Atacama; in the Black Forest (Baden-Württemberg), Odenwald (Hesse), near Sankt Andreasberg (Lower Saxony) and in the Ore Mountains (Saxony) in Germany; in the French regions of Alsace , Auvergne and Lorraine ; in the Cyclades and Attica in Greece; Powys (Wales) in Great Britain; at Silvermines in County Tipperary , Ireland ; on Honshū in Japan; the Coquihalla Pass ( British Columbia ) and in the Timiskaming District (Ontario) in Canada; at Ouarzazate in Morocco; in Qostanai Province in Kazakhstan; in the Mexican counties of Chihuahua , México and Zacatecas ; in the Russian region of Kamchatka ; Malå in Sweden; in the Swiss canton of Valais ; near Banská Bystrica and Košice in Slovakia; in the “Balcoll Mine” near Falset in Spain; in Czech Bohemia ; in the mountains of Rudabánya in Hungary; as well as in several regions of the USA .

morphology

The crystals of the xanthocone have a predominantly tabular habit according to {001}. By twinning often flat, pseudo-orthorhombic or arise as strips by [010] elongated shapes with a length of about 0.5 cm.

Crystal structure

Xanthocone crystallizes monoclinically in the space group C 2 / c (space group no. 15) with the lattice parameters a = 12.00  Å ; b = 6.26 Å; c = 17.08 Å and β = 110.0 ° and 8 formula units per unit cell .

See also

Individual evidence

  1. ↑ Wolfgang Brendler: Mineral collections; a manual and auxiliary book for the creation and maintenance of mineralogical collections . W. Engelmann Verlag, Leipzig, 1912 (excerpt available online)
  2. ↑ Webmineral - Xanthoconite (English)
  3. ↑ a b American Mineralogist Crystal Structure Database - Xanthoconite (English, 1993)
  4. ↑ a b c d Handbook of Mineralogy - Xanthoconite (English, PDF 61.9 kB)
  5. ^ Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 119 .
  6. ↑ a b August Breithaupt (1840): Xanthocon, a new member of the order of the diaphragms , p. 68.
  7. ↑ MinDat - Localities for Xanthoconite (English)
  8. ↑ American Mineralogist Crystal Structure Database - Xanthoconite (English, 1993)
  9. ^ Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 119 .

literature

Web links

Commons : Xanthoconite  - collection of images, videos and audio files