Stephanite
| Stephanite | |
|---|---|
 (size: 2.5 × 2.1 × 1.5 cm) |
|
| General and classification | |
| other names |
|
| chemical formula |
|
|
Mineral class (and possibly department) |
Sulfides and sulfosalts |
|
System no. to Strunz and to Dana |
2.GB.10 ( 8th edition : II / E.06) 02/03/04/01 |
| Similar minerals | Selenostephanite, Arcubisite, Fettelite |
| Crystallographic Data | |
| Crystal system | orthorhombic |
| Crystal class ; symbol | orthorhombic-pyramidal mm 2 |
| Room group (no.) | Cmc 2 1 (No. 36) |
| Lattice parameters | a = 7.84 Å ; b = 12.47 Å; c = 8.54 Å |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | 2 to 2.5 |
| Density (g / cm 3 ) | 6.2 to 6.3 |
| Cleavage | imperfect after {010}, indistinct after {021} |
| Break ; Tenacity | shell-like |
| colour | Lead-gray to iron-black, in rare cases it turns black or colored |
| Line color | black |
| transparency | opaque |
| shine | Metallic luster |
Stephanite , as Sprödglaserz , Sprödglanzerz and Schwarzgültigerz known is a mineral from the mineral class of " sulfides and sulfosalts " that abound in various localities in part, but altogether not widespread. It crystallizes in the orthorhombic crystal system with the composition Ag 5 [S | SbS 3 ], so it is chemically a silver - antimony - sulfosalt.
Stephanite mostly develops short, prismatic to needle-like and longitudinally striped crystals , but also rosette-shaped, step-shaped or massive mineral aggregates of lead-gray to iron-black color with black streak color . In the air it occasionally turns matt black or brightly colored. The surfaces of fresh samples have a metallic sheen .
Special properties
In front of the soldering tube on carbon, stephanite first cracks and then melts, whereby a layer of antimony (III) oxide forms. Melted with soda forms a grain of silver. Stephanite is decomposed by dilute nitric acid with the precipitation of sulfur and antimony (III) oxide.
Etymology and history
Stephanite was already known to the miners in the Middle Ages as a rich silver ore, but under the names brittle glass ore and Röschgewächs (Middle High German for fresh, hard, brittle or also crispy, crispy) in contrast to the soft vegetation , today's silver luster or acanthite . Abraham Gottlob Werner (1789) also adopted the term brittle glass ore in his mineralogical records. By shifting sounds, however, in Werner's time, “glas” changed to “gloss”, which is why Friedrich Hausmann's Handbuch der Mineralogie (1813) , for example, used the term brittle ore . Occasionally black valid ore , black gold or more rarely black ore based on the often black color of stephanite were also in circulation.
The name Stephanit, which is still valid today, was given to the mineral in 1845 by Wilhelm Ritter von Haidinger , who named it after Archduke Stephan of Austria .
The Freiberg mining district in Saxony is the type locality .
classification
Even in the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the stephanite belonged to the mineral class of "sulfides and sulfosalts" and there to the department of "sulfosalts", where together with arcubisite , fettelite and selenostephanite it belongs to the unnamed group II / E.06 made.
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 stephanite to the class of “sulfides and sulfosalts”, but in the newly defined section of “sulfarsenides, sulfantimonides, sulfbismutides” " a. This is further subdivided according to the crystal structure and the possible presence of additional sulfur in the formula, so that the mineral according to its structure and its composition in the sub-section "Island sulfarsenides (Neso sulfarsenides) etc., with additional sulfur (S)" is to be found where only together with selenostephanite the "stephanite group" named after him with the system no. 2.GB.10 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns stephanite to the class of "sulfides and sulfosalts" and there in the department of "sulfosalts". Here he is together with selenostephanite in the "stephanite group" named after him with the system no. 03.02.04 within the subdivision of " Sulphosalts with the ratio z / y = 4 and the composition (A + ) i (A 2+ ) j [B y C z ], A = metals, B = semi-metals, C = non-metals " to find.
Education and Locations
Stephanite forms hydrothermally in geologically active (recent) fault zones in the earth's crust. There it is mainly found in silver deposits, accompanied by acanthite , galena , solid silver, prostite , pyrite , sphalerite and tetrahedron .
So far (as of 2012) around 500 sites for stephanite are known worldwide. In addition to its type locality Freiberg, where the mineral appeared in many pits in the area, it could also be found in Germany in several pits near Annaberg-Buchholz , Johanngeorgenstadt , Marienberg , Bärenstein and Schneeberg in Saxony as well as in many other places in Baden-Württemberg , Bavaria , Hesse , North Rhine-Westphalia and Lower Saxony can be found.
In Austria, stephanite was found at some sites in Carinthia , Salzburg and Styria and in Switzerland only a few sites are known in the canton of Valais (Binntal, Lötschental, Martigny).
Known due to unusual stephanite finds with crystals several centimeters in size are, among others, Příbram (German: Pibrans, older also Freiberg in Böhmen) and Jáchymov (German Sankt Joachimsthal) in the Czech Republic, as well as the Chispas mine near Arizpe in the Mexican state of Sonora.
Other locations are in Argentina, Australia, Bolivia, Bulgaria, Chile, China, Ecuador, France, Greece, Honduras, India, Italy, Japan, Canada, Kazakhstan, Colombia, Morocco, Norway, Peru, on the Philippines, in Poland , Portugal, Romania, Russia, Sweden, Slovakia, Spain, Tajikistan, Hungary, Uzbekistan, the United Kingdom (Great Britain) and the United States of America (USA).
Crystal structure
Stephanite crystallizes in the orthorhombic crystal system in the space group Cmc 2 1 (space group no. 36) with the lattice parameters a = 7.84 Å ; b = 12.47 Å and c = 8.54 Å as well as four formula units per unit cell .
use
Due to the silver content of up to 68%, stephanite is an important silver ore .
See also
literature
- John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols: Stephanite , in: Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 61.6 kB )
Web links
- Mineral Atlas: Stephanite (Wiki)
- Webmineral - stephanite (Engl.)
Individual evidence
- ↑ 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. 122 .
- ↑ a b c Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1979, ISBN 3-342-00288-3 , p. 343 .
- ↑ Webmineral - Stephanite (English)
- ↑ Hans Lüschen: The names of the stones. The mineral kingdom in the mirror of language . Ott Verlag, Thun and Munich 1968, p. 226, 324 .
- ^ Helmut Schrätze, Karl-Ludwig Weiner: Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp. 292 .
- ^ W. Haidinger : Second class: Geogenide. XIV. Order. Shine. VIII. Melange. Stephanite. In: Handbook of determining mineralogy. In Braumüller and Seidel, Vienna 1845, p. 570 ( PDF 440 kB ; p. 9)
- ↑ Franz von Kobell : The mineral names and the mineralogical nomenclature. Gotta'sche Buchhandlung, Munich 1853, p. 24 ( available online at bavarica.digitale-sammlungen.de )
- ↑ Mineralienatlas: Freiberg, Revier (location description and mineral list)
- ↑ MinDat - Stephanite (English)
- ↑ Petr Korbel, Milan Novák: Mineral Encyclopedia . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 54 ( Dörfler Natur ).
- ↑ Mindat - Localities for stephanite
- ^ W. Pohl: W. & WE Petrascheck's deposit theory. 4th edition. E. Schweizerbart'sche Verlagsbuchhandlung (Nägele and Obermiller), Stuttgart 1992, p. 193. ISBN 3-510-65150-2 .