Sartorite

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Sartorite
Sartorite-291308.jpg
Sartorite (shiny metallic) in dolomite from the Binntal , Valais, Switzerland
General and classification
chemical formula PbAs 2 S 4
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.HC.05 ( 8th edition : II / E.25)
07/03/08/01
Crystallographic Data
Crystal system monoclinic pseudoorthorhombic
Crystal class ; symbol 2 / m
Space group P 2 1 / n
Lattice parameters a  = 19.62  Å ; b  = 7.89 Å; c  = 4.19 Å
β  = 90 °
Formula units Z  = 4
Twinning often along {100}
Physical Properties
Mohs hardness 3
Density (g / cm 3 ) 5.39
Cleavage {100} good
Break ; Tenacity shell-like
colour white, gray, rarely with deep red internal reflections
Line color dark brown
transparency opaque
shine shiny metal

Sartorite ( binnite , scleroclase , arsenomelane , lead arsenic ) is a very rare mineral from the mineral class of sulphides and sulphosalts . It crystallizes in the monoclinic crystal system with the chemical composition PbAs 2 S 4 .

Sartorite forms elongated, prismatic crystals up to ten centimeters in length, which can have round holes and often occur in parallel groups. The prism surfaces often show surface stripes in the longitudinal direction due to repeated twinning according to {100}. The crystals are opaque gray-black with a metallic sheen. In reflected light, polished sections appear white with barely visible pleochroism and rare deep red internal reflections.

Etymology and history

The mineral was first found in 1868 by James Dwight Dana in the type locality , the "Lengenbach mine" in the Binn valley , canton of Valais ( Switzerland ). It was named after the Göttingen geology professor Wolfgang Sartorius von Waltershausen , who was the first to make the new mineral known.

classification

In the Strunz system , sartorite is classified as sulfides and sulfosalts. It is counted among the sulfo salts. In the eighth edition , it formed a group with Guettardit , Liveingit , Rathit and Twinnit . In the ninth edition , with Baumhauerite , Baumhauerit-2a , Dufrénoysite , Guettardite, Liveingite, Marumoite , Parapierrotite , Pierrotite , Rathite, Twinnit and Veenit, it belongs to a group of sulphosalts with tin (II) sulphide as a model, which only contain lead .

In the systematics of minerals according to Dana , sartorite forms a subgroup of sulfosalts with guettardite , twinnite and marumoite with the system number 3.7.8 , whose general chemical composition is the ratio z / y = 2 and the formula (A + ) i (A 2+ ) j [B y C z ], A = metals, B = semi-metals, C = non-metals.

According to the latest IMA classification of sulfosalts Sartorit belongs together with Sartorit-9c , Twinnit and Guettardit to isotype Sartoritgruppe. Together with the structurally related minerals of the Baumhauerite type, Dufrénoysite type and Pierrotite type, Sartorite is part of the homologous Sartorite series in the family of lead sulfosalts with large 2-dimensional fragments that relate to the PbS / SnS structure type let back.

Education and Locations

The mineral forms under hydrothermal conditions when arsenic-rich solutions react with galena (PbS). As a result of this conversion, a series of structurally related sulfosalts with increasing As contents can be found in the type locality (Lengenbach, Switzerland), starting with Jordanite , followed by Dufrénoysite , Liveingite , Baumhauerite , Rathite and finally Sartorite.

The type locality is the Lengenbach mine, Binntal in the canton of Valais , Switzerland . Sartorite is found here in dolomite together with galena , pyrite , tennantite , dufrénoysite , rathite and realgar as well as hatchite and seligmannite .

In addition to the type locality and two other sites in the Binn valley, other finds from Cerro Redondo in the Argentine province of Jujuy , Nagybörzsöny in Hungary , Seravezza in Italy , Takarada in Japan , Silverton in Colorado and Fowler in New York ( United States ) are known.

Crystal structure

Sartorite crystallizes in the monoclinic crystal system in the space group P2 1 / n with the lattice parameters a  = 19.62  Å ; b  = 7.89 Å, c  = 4.19 Å and β = 90 ° as well as four formula units per unit cell .

See also

Individual evidence

  1. ↑ a b Handbook of Mineralogy (PDF; 63 kB)
  2. ↑ A System of Mineralogy: Sartorite (PDF; 148 kB) , accessed on October 31, 2009
  3. ^ List of minerals according to Dana at webmineral.com
  4. ↑ Sufosalt systematics: a review. (PDF; 2.2 MB)
  5. ↑ Disordered intergrowths in lead-arsenic sulfide minerals and the Paragenesis of the sartorite-group minerals (PDF; 752 kB)
  6. ↑ Handbook of Mineralogy (PDF; 63 kB)
  7. ↑ Another step toward understanding the true nature of sartorite
  8. ↑ Handbook of Mineralogy (PDF; 63 kB)

literature

  • Sartorit in: Anthony et al .: Handbook of Mineralogy , 1990, 1, 101 ( pdf ).
  • Dana JD, Brush GJ (1868) 105. Sartorite, in: A System of Mineralogy, Fifth Edition , John Wiley and Sons New York 87-88, PDF 144KB (en).
  • Peter Berlepsch, Thomas Armbruster, Emil Makovicy, Dan Topa (2003): Another step toward understanding the true nature of sartorite: Determination and refinement of a ninefold superstructure; American Mineralogist , Volume 88, 450–461, (PDF, 2.36MB)
  • Alan Pring (1990): Disordered intergrowths in lead-arsenic sulfide minerals and the Paragenesis of the sartorite-group minerals; American Mineralogist , Volume 75, 289–294, (PDF 733KB)
  • A. Pring, T. Williams, R. Withers (1993): Structural modulation in sartorite: An electron microscope study; American Mineralogist , Volume 78, 619–626, (PDF 960KB)

Web links

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