Semseyite

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Semseyite
Semseyite-119346.jpg
Semseyite from Baia Sprie, Maramures, Romania (size 11.5 cm × 7.2 cm × 3.5 cm)
General and classification
chemical formula Pb 9 Sb 8 S 21
Mineral class
(and possibly department) 		Sulphides
System no. to Strunz
and to Dana 		2.HC.10d ( 8th edition : II / E.21)
06/03/20/04
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group C 2 / c (No. 15)Template: room group / 15
Lattice parameters a  = 13.60  Å ; b  = 11.94 Å; c  = 24.45 Å
β  = 106.0 °
Formula units Z  = 4
Physical Properties
Mohs hardness 2.5
Density (g / cm 3 ) measured: 6.03; calculated: 6.12
Cleavage completely after {112}
Break ; Tenacity brittle
colour lead gray, black
Line color black
transparency opaque
shine Metallic gloss, matt tarnish

Semseyite is a rather seldom occurring mineral from the mineral class of " sulfides and sulfosalts " with the chemical composition Pb 9 Sb 8 S 21 and thus consists of lead , antimony and sulfur in a ratio of 9: 8: 21. Structurally, semseyite belongs to the sulfosalts.

The mineral is opaque in every form, crystallizes in the monoclinic crystal system and usually develops tabular to prismatic crystals up to about two centimeters in size, but can also be found in the form of rosette-shaped mineral aggregates from lead-gray to black in color. Fresh samples show a metallic sheen , which however tarnishes and becomes matt over time in the air.

Etymology and history

Andor of Semsey (1833-1923)

Semseyite was first found in the " Baia Sprie mine " (Felsöbánya mine) in Romania and in 1881 by József Sándor Krenner (1839–1920). He named the mineral after Andor von Semsey (1833–1923), a Hungarian nobleman and amateur mineralogist.

classification

Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the semseyite belonged to the mineral class of "sulfides and sulfosalts" and there to the department of "sulfosalts (S: As, Sb, Bi = x)", where it belongs together with Fülöppit , Heteromorphit , Plagionit and Rayit formed the unnamed group II / E.21 .

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 semseyite to the class of "sulfides and sulfosalts", but there in the department of "sulfosalts with SnS as a model" . 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 “Only with lead (Pb)”, where it only belongs to the unnamed group 2.HC.10d together with Rayit forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns semseyite to the class of "sulfides and sulfosalts" and there in the department of "sulfosalts". Here he is the only member together with the " Fülöppit group (monoclinic: C2 / c contains Pb, Sb) " with the system no. 06/03/20 within the subsection “Sulphosalts with the ratio 2.0 <z / y <2.49 and the composition (A + ) i (A 2+ ) j [B y C z ], A = metals, B = semi-metals , C = non-metals ”.

Crystal structure

Semseyite crystallizes in the monoclinic crystal system in the space group C 2 / c (space group no. 15) with the lattice parameters a = 13.60 Å , b = 11.94 Å, c = 24.45 Å and β = 106.0 ° and four formula units per unit cell . Template: room group / 15

Education and Locations

Semseyite separates in hydrothermal solutions at average temperatures between 300 and 350 ° C. Accompanying minerals include bournonite , jamesonite , quartz , sphalerite and zinckenite .

In addition to its type locality Baia Sprie, the mineral was also found in Romania in the "Mine Herja " ( Baia Mare ) and Satu Mare . Herja is considered to be one of the best deposits of semseyite at all, with mineral finds between one and three centimeters in size and fan-shaped or rosette-shaped in appearance.

As a rather rare mineral formation, semseyite can sometimes be abundant at various sites, but overall it is not very common. Around 160 sites are known to date (as of 2017), including in Jujuy and Salta in Argentina; some regions of the Bolivian Department of Oruro and Department of Potosí ; near Haskovo in Bulgaria; in the Yizhang region of China ; several regions of Germany and France ; some regions of the UK ; in Bhilwara (India); Iran ; Ireland ; the Italian regions of Piedmont and Tuscany ; on Honshū in Japan; in British Columbia and Ontario in Canada; near Obernberg am Brenner in Austria; Peru ; in Maramureș County in Romania; in the eastern and western regions of Siberia ; Slovakia ; Spain ; in Czech Bohemia ; in the Hungarian Pilsen Mountains and some regions of the USA .

See also

literature

Web links

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

Individual evidence

  1. ↑ 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.  136 .
  2. ↑ Webmineral - Semseyite (English)
  3. ↑ a b c d Semseyite . 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; 64  kB ; accessed on September 24, 2017]).
  4. ↑ a b Andreas Kamrath: Geology and mineralogy of the Herja ore deposit ( Memento from June 6, 2014 in the Internet Archive )
  5. ↑ Mindat - Number of localities for Semseyite
  6. ↑ Find location list for Semseyite at the Mineralienatlas and at Mindat