Dadsonite

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Dadsonite
Dadsonite-177546.jpg
Crystal lawn made of needle-like dadsonite from Saint-Pons , Alpes-de-Haute-Provence , France ( total size of the sample: 3.8 × 2.3 × 1.7 cm)
General and classification
other names

IMA 1968-011

chemical formula Pb 23 Sb 25 S 60 Cl
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.HC.30 ( 8th edition : II / E.20)
06/03/08/01
Crystallographic Data
Crystal system triclinic
Crystal class ; symbol triclinic pinacoidal; 1
Room group (no.) P 1 (No. 2)
Lattice parameters a  = 8.276  Å ; b  = 17.392 Å; c  = 19.505 Å,
α  = 83.527 °; β  = 77.882 °; γ  = 89.125 °
Formula units Z  = 1
Physical Properties
Mohs hardness 2.5 (VHN 15 = 226 to 279)
Density (g / cm 3 ) measured: 5.68; calculated: 5.51
Cleavage not defined
Break ; Tenacity not defined
colour lead gray
Line color black
transparency opaque
shine Metallic luster

Dadsonite is a rarely occurring mineral from the mineral class of " sulfides and sulfosalts ". It crystallizes in the triclinic crystal system with the chemical composition Pb 23 Sb 25 S 60 Cl, thus consists of lead , antimony , sulfur and chlorine and structurally belongs to the sulfo salts.

Dadsonite is opaque in every form and develops only small, fibrous to needle-like crystals up to about two millimeters in length with surfaces striped parallel to the longitudinal axis, which are mainly grouped into " steel wool-like " mineral aggregates . Usually the mineral has a lead-gray color and a metallic sheen . Polished surfaces, on the other hand, reflect the light back white with a greenish tinge and blood-red reflections can be observed in oil. Dadsonit left a black line on the whiteboard .

Etymology and history

Was first described in 1969 by Dadsonit John Leslie Jambor (1936-2008), of the minerals by the Canadian mineralogist Alexander Stewart Dadson named, (1906-1958) about its efforts to develop the gold - deposit Yellowknife honor.

For the analysis of dadsonite, Jambor used samples from a total of four localities:

All four sites are therefore considered type localities for dadsonite.

Type material of the mineral is in the Geological Survey of Canada in Ottawa and in the Royal Ontario Museum in Toronto (Register No. M30905) in Canada, in the Mines ParisTech (also École des mines de Paris , English National School of Mines ) in France, in Natural History Museum in London (register no. 1972,11) and in the National Museum of Natural History in Washington, DC, USA (register no. 123240).

classification

Already in the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the dadsonite 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 Launayit , Madocit , Pellouxit , Playfairit , Sorbyit and Sterryit the unnamed group II / E.20 formed.

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 dadsonite to the class of “sulfides and sulfosalts”, although there it belongs to the “sulfosalts with SnS as a model” section . 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 is the only member of the unnamed group 2.HC.30 .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns dadsonite to the class of "sulfides and sulfosalts" and there in the department of "sulfosalts". Here he is the only member of the unnamed group 06/03/08 within the subdivision “ Sulphonic salts with the ratio 2.0 <z / y <2.49 and the composition (A + ) i (A 2+ ) j [B y C z ], A = metals, B = semimetals, C = non-metals ”.

Education and Locations

Dadsonit forms in hydrothermal - veins , where he mostly-sulfosalts lead with other sulphides and associated occurs. Sun was found among others in the Northwest Territories and Ontario in Canada Jamesonit , in Pershing County of Nevada in the United States Robinsonit and in Saint-Pons in the Alpes-de-Haute-Provence in France Bournonite , Boulangerit , Chalkostibit and Zinkenite as Accompanying minerals.

As a rare mineral formation, dadsonite could only be detected at a few sites, whereby so far (as of 2013) a little more than 10 sites are known. In addition to the type localities already mentioned and the only French site, these are the pits of Kamariza near Agios Konstantinos in the Greek municipality of Lavrio (Attica), Seravezza and Stazzema in the Italian province of Lucca (Tuscany), Dúbrava (Liptovský Mikuláš) and Liptovské Kľačany im Žilinský kraj in Slovakia and an antimony mine near Montenartró in the Spanish comarca of Pallars Sobirà .


Crystal structure

Dadsonite crystallizes triclinically in the space group P 1 (space group no. 2) with the lattice parameters a  = 8.276  Å ; b  = 17.392 Å; c  = 19.505 Å; α = 83.527 °; β = 77.882 ° and γ = 89.125 ° as well as one formula unit per unit cell .

See also

literature

  • JL Jambor: Dadsonite (minerals Q and QM), a new lead sulphantimonide. In: Mineralogical Magazine. 1969, Volume 37, pp. 437-441 ( PDF 230.3 kB )
  • Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 , p. 351 .

Web links

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

Individual evidence

  1. ^ A b c d e Emil Makovicky, Dan Topa, William G. Mumme: The crystal structure of dadsonite. In: The Canadian Mineralogist. 2006, Volume 44, pp. 1499–1512 ( PDF 4.7 MB )
  2. ↑ a b c Dadsonite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF kB )
  3. ↑ Mindat - Number of localities for Dadsonite
  4. ↑ Find location list for dadsonite in the Mineralienatlas and in Mindat