Lautit
| Lautit | |
|---|---|
 |
|
| General and classification | |
| chemical formula | CuAsS |
|
Mineral class (and possibly department) |
Sulfides and sulfosalts |
|
System no. to Strunz and to Dana |
2.CB.40 ( 8th edition : II / C.02) 02.12.08.01 |
| Crystallographic Data | |
| Crystal system | orthorhombic |
| Crystal class ; symbol | dipyramidal: mmm |
| Space group | Pnma |
| Lattice parameters | a = 11.347 Å ; b = 3.753 Å; c = 5.453 Å |
| Formula units | Z = 4 |
| Twinning | along {110} |
| Physical Properties | |
| Mohs hardness | 3 to 3.5 |
| Density (g / cm 3 ) | 4.91 |
| Cleavage | Please complete |
| colour | gray-black to black |
| Line color | black |
| transparency | opaque |
| shine | metallic to semi-metallic |
Lautite is a rarely occurring mineral from the mineral class of sulfides and sulfosalts . It crystallizes in the orthorhombic crystal system with the chemical composition CuAsS and forms up to 2.3 cm long, prismatic or tabular black crystals , but also occurs in the form of masses or grains.
Etymology and history
The mineral was first found in 1880 in the Rudolfschacht mine near Lauta in Saxony . The unknown black mineral, similar to enargite , was examined by Friedrich August Frenzel and named after its type locality .
classification
In the Strunz system , Lautite is counted among the metal sulfides with a ratio of metal to sulfur, selenium or tellurium of 1: 1. After the 8th edition , it forms its own group. In the 9th edition , too, it forms a separate subgroup of sulfides with zinc , iron , copper or silver .
In the Dana system , it forms a subgroup of sulfides, selenides and tellurides with the composition A m B n X p , with (m + n): p = 1: 2.
Education and Locations
Lautite forms in veins under hydrothermal conditions at medium temperatures. Depending on where it was found, it is associated with arsenic , tennantite , prostite , chalcopyrite , galena and barite (in the type locality); Kutinaite and paxite (in Nieder-Beerbach) or arsenic, bismuth , tennantite, lollingite , rammelsbergite , prostite and quartz (Sainte-Marie-aux-Mines)
Some sites are known of the mineral. In addition to the type locality and other places in the Ore Mountains , Lautit was found in Sankt Andreasberg in the Harz , Nieder-Beerbach in the Odenwald , Hausach , Schenkenzell and Titisee-Neustadt in the Black Forest , Flatschach in Austria , Sainte-Marie-aux-Mines in France , Isérables in the Switzerland , Cochrane in Canada , Luqu and Zoigê in China , Sirohi in India , Takab in Iran , Kombat in Namibia and Coconino County in Arizona / USA.
Crystal structure
Lautite crystallizes in the orthorhombic crystal system in the space group P nma with the lattice parameters a = 11.347 Å , b = 3.753 Å and c = 5.453 Å as well as four formula units per unit cell . Lautite thus has a structure similar to sphalerite with Cu [AsS 3 ], As [CuAs 2 S] and S [Cu 3 As] tetrahedra.
See also
Individual evidence
- ↑ a b Luca Bindi, Tiziano Catelani, Laura Chelazzi, Paola Bonazzi: Reinvestigation of the crystal structure of lautite, CuAsS. In: Acta Crystallographica Section E Structure Reports Online. 64, 2008, pp. I22-i22, doi : 10.1107 / S1600536808004492 .
- ↑ A. Frenzel: Lautit. In: Tschermaks Mineralogische und Petrographische Mitteilungen. 1881, 3, pp. 515–516 ( full text (PDF file; 225 kB)).
- ^ New Dana Classification of Sulfide Minerals
- ↑ Luca Bindi, Tiziano Catelani, Laura Chelazzi, Paola Bonazzi: Reinvestigation of the crystal structure of lautite, CuAsS. In: Acta Crystallographica Section E Structure Reports Online. 64, 2008, pp. I22-i22, doi : 10.1107 / S1600536808004492 .
literature
- Lautit in: Anthony et al .: Handbook of Mineralogy , 1990, 1, 101 ( pdf ).
