Clausthalit

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Clausthalit
Clausthalite-522431.jpg
Clausthalite from the Brummerjan mine, Zorge (Walkenried) , Lower Saxony, Germany (field of view 1.5 cm)
General and classification
other names

Selenium lead

chemical formula PbSe
Mineral class
(and possibly department)
Sulfides and sulfosalts - sulfides with Me: S, Se, Te = 1: 1
System no. to Strunz
and to Dana
2.CD.10 ( 8th edition : II / B.11)
08/02/01/02
Similar minerals Galena
Crystallographic Data
Crystal system cubic
Crystal class ; symbol cubic hexakisoctahedral; 4 / m  3  2 / m
Space group Fm 3 m (No. 225)Template: room group / 225
Lattice parameters a  = 6.121  Å
Physical Properties
Mohs hardness 2.5 to 3 (VHN 100 = 44–49)
Density (g / cm 3 ) measured: 7.8 to 8.22; calculated: 8.275
Cleavage good after {100}, {010} and {001}
Break ; Tenacity grainy; brittle
colour lead gray to bluish
Line color grayish black
transparency opaque
shine Metallic luster
Other properties
Chemical behavior soluble in sulfuric and nitric acid

Clausthalite , also known as selenium lead out of date , is a rather seldom occurring mineral from the mineral class of "sulfides and sulfosalts" with the chemical composition PbSe, ie it consists of equal parts of lead and selenium . Chemically speaking, the mineral is thus a lead selenide .

Clausthalite crystallizes in a cubic crystal system , but does not develop any crystals that are visible to the naked eye, but is mainly found in the form of granular to massive mineral aggregates and speckles of lead-gray to bluish color.

Etymology and history

The mineral was found in 1832 by François Sulpice Beudant near Clausthal-Zellerfeld in the Upper Harz Mountains and named after its type locality , the Clausthal district. The St. Lorenz mine is the exact type locality .

classification

Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the Clausthalite belonged to the mineral class of "sulfides and sulfosalts" and there to the department of "sulfides with M: S = 1: 1" (PbS type and relatives) , where together with Alabandin , Altait , Galenit , Niningerit and Oldhamit he created the "Galenit series" with the system no. II / B.11 formed.

In the last revised and updated Lapis mineral directory by Stefan Weiß in 2018 , which, out of consideration for private collectors and institutional collections, is still based on this classic system of Karl Hugo Strunz , the mineral was given the system and mineral number. II / C.15-50 . In the "Lapis system", this corresponds to the section "Sulphides with metal: S, Se, Te ≈ 1: 1", where Clausthalite, together with Alabandin, Altaite, Crerarite , Galena, Keilite , Niningerite and Oldhamite, form an independent but unnamed group forms.

The 9th edition of Strunz's mineral systematics , valid since 2001 and updated by the International Mineralogical Association (IMA) until 2009, also classifies Clausthalite in the category of "Metal sulfides, M: S = 1: 1 (and similar)". However, this is further subdivided according to the predominant metals ( cations ) in the compound , so that the mineral can be found according to its composition in the sub-section "with tin (Sn), lead (Pb), mercury (Hg) etc.", where it together with Alabandin, Altait, Galenit, Keilit, Niningerit and Oldhamit the "Galenitgruppe" with the system no. 2.CD.10 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Clausthalite to the class of "sulfides and sulfosalts" and there in the department of "sulfide minerals". Here he is also in the "Galena group (isometric: Fm 3 m )" with the system no. 02.08.01 within the subsection " Sulphides - including selenides and tellurides - with the composition A m B n X p , with (m + n): p = 1: 1 ".

Chemism

In chemically pure form Clausthalit consists of 72.41% lead and 27.59% selenium with a molecular weight of 286.971 g / mol. Natural Clausthalites can, however, also contain cobalt , iron , copper , mercury and / or silver as foreign admixtures .

Clausthalit and galena form a series of mixed crystals that are seamless at 300 ° C. For this reason, many galena deposits contain a certain percentage of selenium.

Crystal structure

Crystal structure of Clausthalit

Clausthalite crystallizes in the cubic crystal system in the space group Fm 3 m (space group no. 225) and is isotype to the sodium chloride structure . The lattice parameter a is 6.121  Å . The unit cell has slightly longer axes than the isotypic galena (PbS, 5.936 Angstroms). This is due to the somewhat larger ionic radius of the selenide ions (Se 2− ) in Clausthalite compared to the sulfide ions (S 2− ) in galena. Since sulfur and selenium can often replace each other in crystal structures , the lattice parameter of a mixed crystal Pb (S, Se), depending on the proportion of the corresponding element, can be between the values ​​mentioned above. Template: room group / 225

properties

Clausthalit can be dissolved with sulfuric and nitric acid . Furthermore, when heated in front of the soldering tube, it develops a strong, radish-like to putrid odor, which is typical for selenium and selenium compounds with this method.

Modifications and varieties

Lerbachite

The variety Lerbachit (Hg, Pb) Se, locally named after the mountain town of Lerbach , consists of a mixture of Clausthalite and Tiemannite .

The micromineral red bearite is only contained in Clausthalit .

Education and Locations

Clausthalite is probably the most common natural selenide. The mineral forms hydrothermally in low-sulfur deposits as well as in mercury deposits . In addition to other selenides such as berzelianite , klockmannite , tiemannite and umangite , solid gold , stibiopalladinite and uraninite can occur as accompanying minerals .

As a rather rare mineral formation, Clausthalite can sometimes be abundant at different sites, but overall it is not very common. So far (as of 2017) around 270 sites are known. In addition to its type locality Grube St.Lorenz near Clausthal-Zellerfeld, the mineral occurred in Germany in other places in Lower Saxony, Baden-Württemberg ( Black Forest ), Bavaria, Hesse, North Rhine-Westphalia, Saxony-Anhalt ( Harz ) and Saxony ( Ore Mountains ) .

In Austria, the mineral has so far only been found in an unnamed quarry near the Judenbauer ( Kirchschlag municipality in the Bucklige Welt ) in Lower Austria, on Eselberg near Altenberg an der Rax in Styria and in a limestone quarry near Lorüns in Vorarlberg.

In Switzerland, Clausthalit has so far been found mainly in the cantons of Aargau and Valais .

Other locations are in Argentina, Australia, Belgium, Bolivia, Brazil, Bulgaria, China, Finland, France, Greece, Greenland, Italy, Japan, Canada, the Democratic Republic of the Congo, Japan, Morocco, Mexico, Norway, Poland, Romania , Russia, Zimbabwe, Slovakia, Spain, South Africa, Sweden, Tanzania, Turkey, the Czech Republic, Uzbekistan, the United Kingdom (UK) and the United States of America (USA).

use

Both lead and selenium are extracted from Clausthalite, so the entire mineral can be processed. Clausthalite is particularly important as selenium ore, and galena is more important than lead ore. When lead is extracted , the selenide contained is separated and serves as a source for elemental selenium and other selenium compounds.

See also

literature

  • FS Beudant: Traité Élémentaire de Minéralogie. Claushalie, plomb sélénié . 2nd Edition. Chez Verdière Libraire-Éditeur, Paris 1832, p. 531-534 .
  • Robert G. Coleman: The natural occurrence of Galena-Clausthalite solid solution series . In: American Mineralogist . tape 44 , no. 1-2 , 1959, pp. 166–175 ( minsocam.org [PDF; 649 kB ; accessed on December 28, 2016]).
  • Petr Korbel, Milan Novák: Encyclopedia of Minerals . Dörfler Verlag GmbH, Eggolsheim 2002, ISBN 978-3-89555-076-8 , p. 35 .
  • Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 442 (first edition: 1891).

Web links

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

Individual evidence

  1. a b c Helmut Schrätze , Karl-Ludwig Weiner : Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp.  208 .
  2. ^ A b Y. Noda, K. Masumoto, S. Ohba, Y.Saito, K. Toriumi, Y. Iwata, I. Shibuya: Temperature dependence of atomic thermal parameters of lead chalcogenides, PbS, PbSe and PbTe- . In: Acta Crystallographica . C43, 1987, pp. 1443–1445 , doi : 10.1107 / S0108270187091509 (English).
  3. a b c d Clausthalite . 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; 59  kB ; accessed on August 23, 2019]).
  4. Type locality Grube St.Lorenz at the Mineralienatlas and at Mindat
  5. 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 .
  6. Ernest H. Nickel, Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF 1703 kB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed April 25, 2019 .
  7. ^ David Barthelmy: Clausthalite Mineral Data. In: webmineral.com. Retrieved on August 23, 2019 .
  8. Christian Ernst: Clausthalers discover new mineral in the Harz. In: tu-clausthal.de. Clausthal University of Technology , August 21, 2019, accessed on August 23, 2019 .
  9. Sensation in the Harz Mountains: the first new mineral discovered since 1908. In: harzkurier.de. Harz Kurier , August 22, 2019, accessed on August 23, 2019 .
  10. Localities for Clausthalite. In: mindat.org. Hudson Institute of Mineralogy, accessed August 23, 2019 .
  11. List of localities for clausthalite in the Mineralienatlas and Mindat