Boulangerite

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Boulangerite
Boulangerite, Calcite - Stari Trg Mine, Trepca, Kosovo1.jpg
Some calcites on a bed of boulangerite from the Stari Trg Mine, Trepča , Kosovo
General and classification
chemical formula Pb 5 Sb 4 S 11
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.HC.15 ( 8th edition : II / E.19)
05/03/02/01
Similar minerals Cosalite , plumosite
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol orthorhombic-dipyramidal 2 / m 2 / m 2 / m
Space group Pnam
Lattice parameters a  = 23.49  Å ; b  = 21.24 Å; c  = 4.02 Å
Formula units Z  = 4
Physical Properties
Mohs hardness 2.5 to 3
Density (g / cm 3 ) 6.2
Cleavage indistinct after {001} and {010}
Break ; Tenacity uneven, pliable
colour grey black
Line color black
transparency opaque
shine Metallic gloss, silk gloss

Boulangerite is a frequently occurring mineral from the mineral class of " sulfides and sulfosalts ". It crystallizes in the orthorhombic crystal system with the chemical composition Pb 5 Sb 4 S 11 and develops mostly granular or fine-fiber aggregates , but rarely also needle-like, striped crystals of gray-black color with black streak color .

Boulangerite is opaque and shows a metallic sheen when crystalline , while fibrous aggregates have a silk sheen. Its Mohs hardness fluctuates between 2.5 and 3, so it can hardly be scratched with a fingernail, but it can be scratched with a copper coin.

Etymology and history

Boulangerite was first discovered in the commune of Molières in the French department of Gard and analyzed first by Charles Louis Boulanger (1810–1849), a French mining engineer, and again in 1837 by Thaulow, whose analysis showed a content of 18.86% sulfur , 24, Found 60% antimony and 55.57% lead . The mineral was named after Boulanger.

classification

In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the boulangerite belonged to the mineral class of "sulfides and sulfosalts" and there to the general department of "sulfosalts", where together with Ardait , Falkmanit , Jaskólskiit , Moëloit , Pillait and Plumosit formed an independent group.

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the IMA, assigns boulangerite to the extended class of "sulfides and sulfosalts (sulfides, selenides, tellurides, arsenides, antimonides, bismuthides, sulfarsenites, sulfantimonites, sulfbismuthites)" and there in the department of "sulfosalts with SnS as a model". However, this section is further subdivided according to the type of cations involved , 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 together with Falkmanite and Plumosite .15 forms.

The systematics of minerals according to Dana also assigns the boulangerite to the class of "sulfides and sulfosalts" and there in the department of "sulfosalts". Here he is together with Falkmanit in the unnamed group 05/03/02 within the subdivision of “ Sulphosalts with the ratio 2.5 <z / y <3 and the composition (A + ) i (A 2+ ) j [B y C z ], where A = metals, B = semimetals, C = non-metals ”.

Education and Locations

Heavily etched quartz crystal with a "beard" made of boulangerite

Boulangerite is formed by hydrothermal processes at low to medium temperatures. Accompanying minerals include various lead sulfide and sulfo salts such as arsenopyrite , galena , pyrite , sphalerite and stibnite , but also siderite and quartz .

Boulangerite has so far (as of 2010) been detected at around 600 sites worldwide, including in Afghanistan , Egypt , Argentina , Armenia , Australia , Bolivia , Bulgaria , Chile , China , Germany , Ecuador , Finland , France , Georgia , Ghana , Greece , Greenland , India , Indonesia , Iran , Ireland , Italy , Japan , Canada , Kazakhstan , Kyrgyzstan , Colombia , North and South Korea , Croatia , Malaysia , Morocco , Macedonia , Mexico , Mongolia , Namibia , Norway , Austria , Peru , Poland , Romania , Russia , Sweden , Switzerland , Serbia , Slovakia , Slovenia , Spain , South Africa , the Czech Republic , Ukraine , Hungary , the United Kingdom (Great Britain) and the United States of America (USA).

Crystal structure

Boulangerite crystallizes orthorhombically in the space group Pnam with the lattice parameters a  = 23.49  Å ; b  = 21.24 Å and c  = 4.02 Å and 4 formula units per unit cell .

See also

Individual evidence

  1. ^ A b 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. 134 .
  2. ↑ Mindat - locality "Molières, Gard, Languedoc-Roussillon, France"
  3. ^ Robert Allan, Carl Friedrich Alexander Hartmann: Die Mineralogie . Godf. Basse Verlag, Quedlinburg and Leipzig 1838, p. 239 . (available online from Google Book Search )
  4. ↑ Mindat - Localities for Boulangerite (English)
  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. 134 .

literature

Web links

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