Cosalite

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Cosalite
Cosalit - Willroth, Westerwald.jpg
General and classification
chemical formula Pb 2 Bi 2 S 5
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.JB.10 ( 8th edition : II / E.34)
05/03/09/01
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol orthorhombic-dipyramidal 2 / m 2 / m 2 / m
Space group Pbnm
Lattice parameters a  = 19.098  Å ; b  = 23.89 Å; c  = 4.057 Å
Formula units Z  = 8
Physical Properties
Mohs hardness 2.5 to 3
Density (g / cm 3 ) 6.86 to 6.99 (calculated: 7.12)
Cleavage no
Break ; Tenacity uneven
colour silver white, lead gray
Line color black
transparency opaque
shine Metallic luster

Cosalite (also Bjelkit ) is a rather rare mineral from the mineral class of " sulfides and sulfosalts ". It crystallizes in the orthorhombic crystal system with the chemical composition Pb 2 Bi 2 S 5 and develops mostly radial, fibrous or massive aggregates , but occasionally also prismatic to needle-like crystals of silver-white or lead-gray color and metallic luster.

Etymology and history

Cosalite was first discovered in 1868 in a silver mine near Cosalá in Mexico and described by Friedrich August Genth , who named the mineral after its type of locality .

classification

In the meanwhile outdated system of minerals according to Strunz (8th edition) , cosalite still belongs to the general division of sulfosalts without any further differentiation. With the revision of Strunz's mineral system in the 9th edition , this section was subdivided more precisely according to the crystal structure with a corresponding mineral model and the cations involved . The Cosalit is now in the new department of “Sulphosalts with PbS as a model” and there as the only one of its group in the sub-department “Galena derivatives with lead (Pb)”.

The common in the English language classification of minerals by Dana also assigns the Cosalit in the Department of thio-a, there, however, in the subsection " thio with the ratio 2.5 <z / y <3 and the general composition (A + ) i ( A 2+ ) j [B y C z ], where A = metal, B = semi-metals, non-metals C = "where he together with Veenit and Dufrenoysit the unnamed group 3.5.9 forms.

Education and Locations

Cosalite forms either in igneous rocks such as pegmatite or through hydrothermal processes in medium- grade deposits . Accompanying minerals include bornite , calcite , chalcopyrite , cobaltite , diopside , pyrite , skutterudite , sphalerite and tremolite .

In addition to its type locality Cosalá, Cosalit was found in Mexico at Candamene and Naica in Chihuahua , Zimapán in Hidalgo and La Cienega in Sonora .

So far, Cosalite has been found at more than 200 sites worldwide (as of 2009), including in some regions of Australia ; the Bulgarian oblasts of Montana , Plovdiv and Smolyan ; Hunan , Shandong , Sichuan and Tibet in China; Bavaria , Hesse , Rhineland-Palatinate and Saxony in Germany; some regions of France ; Greece ; in some regions of Italy ; in several regions of Canada ; Buskerud , Nordland and Telemark in Norway; Carinthia , Salzburg and Vorarlberg in Austria; Poland ; in some regions of Russia ; Sweden ; Switzerland ; Banská Bystrica and Košice in Slovakia; Bohemia and Moravia in the Czech Republic; as well as in many regions of the United States .

Crystal structure

Cosalite crystallizes in the orthorhombic crystal system in the space group Pbnm with the lattice parameters a  = 19.098  Å ; b  = 23.89 Å and c  = 4.057 Å as well as eight formula units per unit cell .

See also

Individual evidence

  1. ↑ a b c Webmineral - Cosalite (English)
  2. ↑ a b American Mineralogist Crystal Structure Database - Cosalite (English, 1974)
  3. ^ Paul Ramdohr , Hugo Strunz : Klockmanns textbook of mineralogy . 16th edition. Ferdinand Enke Verlag, 1978, ISBN 3-432-82986-8 , pp. 481 .
  4. ↑ Mindat - Localities for Cosalit (English)
  5. ↑ American Mineralogist Crystal Structure Database - Cosalite (English, 1974)

literature

  • Petr Korbel, Milan Novák: Encyclopedia of Minerals . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 62 .

Web links

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