Plagionite

from Wikipedia, the free encyclopedia
Plagionite
Plagionite-169955.jpg
Plagionite from "San José Mine", Oruro , Bolivia (size: 3.3 × 3.0 × 1.7 cm)
General and classification
chemical formula Pb 5 Sb 8 S 17
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.HC.10b ( 8th edition : II / E.21)
06/03/20/03
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group C 2 / c (No. 15)Template: room group / 15
Lattice parameters a  = 13.49  Å ; b  = 11.87 Å; c  = 19.98 Å
β  = 107.2 °
Physical Properties
Mohs hardness 2.5 (VHN 100  = 34 to 163)
Density (g / cm 3 ) measured: 5.54; calculated: 5.55
Cleavage very good according to {112}
Break ; Tenacity uneven to shell-like; brittle
colour dark red-brown, lead-gray to black
Line color blackish-lead gray
transparency opaque
shine Metallic luster

Plagionit is a rarely occurring minerals from the mineral class of "sulphides and thio" with the chemical composition Pb 5 Sb 8 S 17 , is structurally the lead - thio-salts .

Plagionite crystallizes in the monoclinic crystal system , is opaque in every form and usually develops thick tabular to prismatic crystals of dark red-brown or lead-gray to black color and metallic luster . But it also occurs in the form of granular to massive mineral aggregates .

Etymology and history

The mineral was first mentioned in 1831 by Johann Ludwig Carl Zincken , who described the blackish-lead-gray crystals as “new spit-luster ore” from the “Graf Jost-Christian-Zeche” near Wolfsberg (Mansfeld-Südharz) in Saxony-Anhalt. In 1833 Gustav Rose examined the mineral more closely and named it based on its oblique crystal axes and thus oblique crystal shapes after the ancient Greek word πλάγιος [plágios] for oblique or oblique. His brother Heinrich Rose carried out the chemical analyzes.

The type material of the mineral is kept in the mineral collection of the Museum für Naturkunde Berlin (register no. 1999-0078).

classification

In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the plagionite belonged to the department of "sulfosalts (S: As, Sb, Bi = x)", where together with Fülöppit , Heteromorphit , Rayit and Semseyit it forms the unnamed group II / E.21 .

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), classifies the plagionite in the newly defined section of “sulfosalts with SnS as a model”. 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.10b .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns plagionite to the class of "sulfides and sulfosalts" and there into the department of "sulfosalts". Here it is together with Fülöppit, Heteromorphit, Rayit and Semseyit in the Fülöppit group (monoclinic: C2 / c contains Pb, Sb) with the system no. 06/03/20 within the subsection “Sulphosalts with the ratio 2.0 <z / y <2.49 and the composition (A + ) i (A 2+ ) j [B y C z ], A = metals, B = semi-metals , C = non-metals ”.

Education and Locations

Plagionit forms in hydrothermal - veins in ore - deposits , where he usually associated with other sulphide minerals such as Andorit , Boulangerit , Franckeit , galena , Geokronit , cassiterite , pyrite , Robinsonit , Semseyit , Twinnit and Zinkenite occurs.

As a rare mineral formation, plagionite could only be detected at a few sites, whereby so far (as of 2013) around 80 sites are known. In addition to its type locality "Graf Jost-Christian-Zeche", the mineral appeared in Germany in several places in the Black Forest such as Oberwolfach and Sulzburg in Baden-Württemberg; in the "Caspari" mine near Uentrop (Arnsberg) and the Brüderbund mine near Eiserfeld in North Rhine-Westphalia, as well as in several places in the Eifel in Rhineland-Palatinate.

In Austria, plagionite is only known from praises in the municipality of Bad St. Leonhard in Lavanttal (Carinthia).

Other locations are in Bolivia, Bulgaria, China, France, India, Iran, Italy, Canada, Kyrgyzstan, Luxembourg, Mexico, Poland, Romania, Serbia, Slovakia, Hungary, the United Kingdom (England and Wales) and the United States States of America (Nevada and Virginia).

Crystal structure

Plagionite crystallizes monoclinically in the space group C 2 / c (space group no. 15) with the lattice parameters a  = 13.49  Å ; b  = 11.87 Å; c  = 19.98 Å and β = 107.2 ° as well as formula units per unit cell . Template: room group / 15

See also

literature

Web links

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

Individual evidence

  1. ↑ a b c d e Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p.  136 .
  2. ↑ a b Plagionite. In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America. 2001 ( PDF 62.4 kB )
  3. ↑ Mindat - Number of locations for plagionite
  4. ↑ Find location list for plagionite in the Mineralienatlas and Mindat .