Umangit
| Umangit | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Cu 3 Se 2 |
|
Mineral class (and possibly department) |
Sulfides and sulfosalts |
|
System no. to Strunz and to Dana |
2.BA.15c ( 8th edition : II / B.03) 05/02/01/01 |
| Crystallographic Data | |
| Crystal system | tetragonal |
| Crystal class ; symbol | tetragonal-scalenohedral; 4 2 m |
| Room group (no.) | P 4 2 1 m (No. 113) |
| Lattice parameters | a = 6.40 Å ; c = 4.28 Å |
| Formula units | Z = 2 |
| Twinning | lamellar twinning |
| Physical Properties | |
| Mohs hardness | 3 (VHN 100 = 88 to 100) |
| Density (g / cm 3 ) | measured: 6.44 to 6.49; calculated: 6.590 |
| Cleavage | indistinct, rectangular |
| Break ; Tenacity | uneven to slightly scalloped |
| colour | blue-black with a reddish tinge |
| Line color | black |
| transparency | opaque |
| shine | Metallic luster |
Umangite is a rarely occurring mineral belonging to the mineral class of the "sulfides and sulfosalts" (including selenides, tellurides, arsenides, antimonides and bismuthides). It crystallizes in the tetragonal crystal system with the idealized chemical composition Cu 3 Se 2 and is thus chemically seen a copper - selenide . For natural Umangiten however, a part of copper, by silver (Ag) replaces be, with silver contents were measured to about 0.5% in various analyzes.
Umangite is opaque and can only be found in the form of granular to massive mineral aggregates . Occasionally, conspicuous, lamellar twinning can also be observed. Fresh samples are dark cherry red in color, playing into violet, and have a metallic sheen . Due to weathering, however, the mineral quickly turns dark purple to blue-black and becomes dull.
With a Mohs hardness of 3, umangite is one of the medium-hard minerals that, like the reference mineral calcite, can be scratched with a copper coin.
Etymology and history
The mineral was first discovered in the Sierra de Umango in the Argentine province of La Rioja and described in 1891 by Friedrich Klockmann , who named it after its type locality .
classification
In the outdated, but partly still in use, 8th edition of the mineral classification according to Strunz , the umangite belonged to the department of "sulfides, selenides and tellurides with the molar ratio of metal: S, Se, Te> 1: 1", where it, together with athabascaite , bellidoite , Berzelianite , crookesite and sabatierite formed the unnamed group II / B.03 .
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 classifies umangite in the category of "Metal sulfides with a molar ratio M: S> 1: 1 (mainly 2: 1)" . This is, however, 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 "with copper (Cu), silver (Ag), gold (Au)", where it is the only member unnamed group forms 2.BA.15c .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns umangite to the class of "sulphides and sulphosalts" and there in the category of "sulphide minerals". Here he is to be found as the only member of the unnamed group 02.05.01 within the subsection “Sulphides - including selenides and tellurides - with the composition A m B n X p , with (m + n): p = 3: 2”.
Education and Locations
Umangite formed hydrothermally at below 112 ° C in ore junctions , where he mostly in paragenesis with other selenides such as, but Berzelianit , Clausthalit , Eukairit , Guanajuatit , Klockmannit , Naumannite and Tiemannite , but also with other sulphide minerals such as chalcopyrite , Cobaltit , Hessit and Pyrite , the carbonates calcite and malachite and the selenite chalcomenite occurs.
As a rare mineral formation, Umangite could only be detected at a few sites, whereby so far (as of 2014) around 70 sites are known. In addition to its type locality Sierra de Umango, the mineral occurred in Argentina in various places in the Sierra de Cacho , near Puerto Alegre in the Famatina department and in the Sañogasta district in the La Rioja province as well as in the Sierra de Cacheuta belonging to the Mendoza province .
In Germany, umangite was found in the Clara mine near Oberwolfach and the former uranium deposit of the Krunkelbach mine near Menzenschwand in Baden-Württemberg; in the " Grube Christa " near Großschloppen in the Fichtelgebirge and in the fluorite mining area near Wölsendorf in Bavaria; the mines "Brummerjan" near Zorge , "Weintraube" near Lerbach (Osterode am Harz) , " Roter Bär " and " Wennsglück " near Sankt Andreasberg and in the Trogtal quarry near Lautenthal in Lower Saxony; in a Grauwacke quarry near Rieder (Ballenstedt) and near Tilkerode- Abberode in Saxony-Anhalt, in the Schlema - Hartenstein district in the Saxon Ore Mountains and in the Lichtenberg opencast mine near Ronneburg in Thuringia.
The only known site in Austria so far is a selenide deposit on Eselberg near Altenberg an der Rax in Styria.
Other locations include Australia, Bolivia, China, the Democratic Republic of the Congo (Zaire), France, Greenland, Canada, Mexico, Namibia, Poland, Russia, Sweden, the Czech Republic, the United Kingdom (England) and the United States of America (Colorado, Washington).
Crystal structure
Umangite crystallizes tetragonally in the space group P 4 2 1 m (space group no. 113) with the lattice parameters a = 6.40 Å and c = 4.28 Å as well as two formula units per unit cell .
See also
literature
- Friedrich Klockmann : Mineralogical communications from the collections of the Bergakademie zu Clausthal. In: Journal for Crystallography and Mineralogy. Volume 19 (1891), pp. 265–275 ( PDF 561.4 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. 299 .
- Petr Korbel, Milan Novák: Encyclopedia of Minerals . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 22 ( Dörfler Natur ).
Web links
- Mineral Atlas: Umangite
- Mindat - Umangite
- Web mineral - Umangite
- Database-of-Raman-spectroscopy - Umangite
- American-Mineralogist-Crystal-Structure-Database - Umangite
Individual evidence
- ↑ a b c d e 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. 63 .
- ↑ a b Umangite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 63.9 kB )
- ^ Helmut Schrätze, Karl-Ludwig Weiner: Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp. 128-129 .
- ↑ Mindat - Number of localities for Umangit
- ↑ Find location list for Umangite at the Mineralienatlas and at Mindat