Clarait
| Clarait | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula |
|
|
Mineral class (and possibly department) |
Carbonates and nitrates |
|
System no. to Strunz and to Dana |
5.DA.30 ( 8th edition : V / E.07) 16b.04.03.01 |
| Crystallographic Data | |
| Crystal system | triclinic |
| Crystal class ; symbol | triklin-pedial; 1 or triclinic pinacoidal; 1 |
| Lattice parameters |
a = 14.28 Å ; b = 8.03 Å; c = 7.27 Å, α = 79.16 °; β = 107.90 °; γ = 99.68 ° |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | 2 |
| Density (g / cm 3 ) | measured: 3.35; calculated: 3.34 |
| Cleavage | completely according to {10 1 0} |
| colour | blue green |
| Line color | not defined |
| transparency | transparent to translucent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n ω = 1.751 n ε = 1.645 |
| Birefringence | δ = 0.106 |
| Optical character | weak biaxial negative |
Clarait is a rarely occurring mineral from the mineral class of " carbonates and nitrates ". It crystallizes in the triclinic crystal system with the idealized chemical composition (Cu, Zn) 15 (CO 3 ) 4 (AsO 4 ) 2 (SO 4 ) (OH) 14 · 7H 2 O and is therefore chemically a water-containing copper - zinc carbonate with additional arsenate , sulfate and hydroxide ions . The elements copper and zinc indicated in round brackets can represent each other in the formula ( substitution , diadochie), but are always in the same proportion to the other components of the mineral.
Clarait is transparent to translucent and only develops small, pseudo-hexagonal or pseudorhombohedral crystals up to about 0.5 millimeters in size and with a glass-like sheen on the surfaces. It is mostly found in the form of spherulitic mineral aggregates and crusty coatings of blue-green color.
Etymology and history
Clarait was first discovered in the Clara mine near Oberwolfach in the Black Forest (Baden-Württemberg) and was recognized as an independent mineral in 1981 by the International Mineralogical Association (IMA) (IMA entry no. 1981-023). The mineral was described by Kurt Walenta and Pete J. Dunn , who named it after its type locality . They published their analysis results and mineral description in 1981 in the science magazine "Chemie der Erde / Geochemistry".
Originally, Walenta and Dunn had determined the chemical formula with (Cu, Zn) 3 [(OH) 4 | CO 3 ] · 4H 2 O. However, the chemical composition was redefined in 2016 and recognized by the IMA (see IMA Newsletter 34, 2017).
Type material of the mineral is stored in the University of Stuttgart (Germany) and in the Smithsonian Institution (USA).
classification
In the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the Clarait belonged to the common class of "carbonates, nitrates and borates" and there to the department of "hydrous carbonates with foreign anions ", where together with callaghanite and decrespignyite (Y) formed the unnamed group V / E.07 .
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the IMA, assigns the Clarait to the reduced class of “carbonates and nitrates”, but also to the section of “carbonates with additional anions; with H 2 O “. This is, however, further subdivided according to the relative size of the cations involved , so that the mineral can be found according to its composition in the sub-section “With medium-sized cations”, where it is the only member of the unnamed group 5.DA.30 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Clarait, like the outdated Strunz system, to the common class of “carbonates, nitrates and borates” and there to the category of “carbonates - hydroxyl or halogen”. Here he is the only member of the unnamed group 16b.04.03 within the subdivision “ Carbonates - Hydroxyl or Halogen with (A) m (B) n (XO 3 ) p Z q • x (H 2 O), with (m + n): p = 8: 1 “.
Crystal structure
Clarait possibly crystallizes triclinic, whereby the space group has not yet been determined, with the lattice parameters a = 14.28 Å ; b = 8.03 Å; c = 7.27 Å; α = 79.16 °; β = 107.90 ° and γ = 99.68 ° and 4 formula units per unit cell .
The hexagonal pseudocell has the lattice parameters a = 26.22 Å and c = 21.56 Å.
Education and Locations
Clarait forms secondarily in oxidized copper-zinc deposits . As accompanying minerals may include, azurite , barite , Devillin , fluorite , gypsum , malachite , Olivenit and quartz occur.
As a rare mineral formation, Clarait could only be proven at a few sites, whereby so far (as of 2013) around 30 sites are known. In addition to its type locality Grube Clara in Baden-Württemberg, the mineral has so far been found in Germany in the "Sulzbach II" mine in the Donaustaufer Revier in Bavaria, in the "Charlotte Magdalena" and "Floßberg" mines near Bad Lauterberg in the Harz in Lower Saxony Slag heaps of the zinc smelter "Friedrich-Wilhelm" near Birkengang and the copper smelter near Kall in North Rhine-Westphalia.
In Austria, Clarait was found on the Feistritz Alp near Feistritz an der Gail , on the Unterbuchach Alp near Kirchbach and in the “Judengras” mine near Podlanig ( Lesachtal ) in Carinthia; at Schwarzleo in the municipality of Leogang in Salzburg and at several locations in the Brixlegg - Rattenberg district (Hof, Silberberg, Sommerau), at the Weißen Schrofen at Ringenwechsel near Schwaz and at Pengelstein near Kitzbühel in Tyrol.
In Switzerland, the mineral was previously found in the “Gosan” and “Termino” mines near Saint-Luc VS , Six-Blanc near Bagnes , Mont Chemin near Martigny and in the Vaashöhle near Granges in the municipality of Sion ( Sion in French ) Canton of Valais found.
In addition, Clarait is only known from the “Salsigne” mine in the French canton of Mas-Cabardès , the “Andrássy I” mine in the Hungarian municipality of Rudabánya , Carrara in the Italian Tuscany and the “La Amorosa” mine near Villahermosa del Rio in the Spanish province of Castellón .
See also
literature
- Kurt Walenta , Pete J. Dunn: Claraite, a new carbonate mineral from the Clara pit (central Black Forest). In: Chemistry of the Earth. Volume 41 (1982), pp. 97-102
- Pete J. Dunn, Michael Fleischer, Roger G. Burns, Adolf Pabst : New mineral names. In: American Mineralogist. Volume 68 (1983), pp. 471-475 ( PDF 948.5 kB ; Clarait p. 1)
- John Leslie Jambor , Andrew C. Roberts: New mineral names. In: American Mineralogist. Volume 88 (2003), pp. 251–255 ( PDF 82.4 kB ; Clarait p. 4)
Web links
Individual evidence
- ↑ a b c U. Hålenius, F. Hatert, M. Pasero, SJ Mills: IMA Commission on New Minerals, Nomenclature and Classification (CNMNC). Newsletter 34 ( PDF; 97 kB )
- ^ A b 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. 312 .
- ↑ Claraite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF; 66 kB )
- ^ A b Kurt Walenta: On the lattice constants of claraite. In: The ore graves. Volume 13 (1999), pp. 20-22 (short version: John Leslie Jambor , Andrew C. Roberts: New mineral names. In: American Mineralogist. Volume 88 (2003), p. 254 ( PDF 82.4 kB ; p. 4)
- ^ A b c d e f Kurt Walenta, Pete J. Dunn: Claraite, a new carbonate mineral from the Clara Mine, (Central Black Forest). In: Chemistry of the Earth. Volume 4 (1982), pp. 97-102 (short version: Pete J. Dunn, Michael Fleischer, Roger G. Burns, Adolf Pabst : New mineral names. In: American Mineralogist. Volume 68 (1983), p. 471 ( PDF 948 , 5 kB ; p. 1)
- ↑ Mindat - Claraite
- ↑ Mindat - Number of localities for Clarait
- ↑ Find location list for Clarait in the Mineralienatlas and in Mindat