Fettelite
| Fettelite | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 1994-056 |
| chemical formula | Ag 24 HgAs 5 S 20 |
|
Mineral class (and possibly department) |
Sulfides and sulfosalts |
|
System no. to Strunz and to Dana |
2.LA.30 ( 8th edition : II / E.06) 02/03/06/02 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic sphenoid; 2 |
| Room group (no.) | C 2 (No. 5) |
| Lattice parameters |
a = 26.030 Å ; b = 15.059 Å; c = 15.524 Å β = 90.45 ° |
| Formula units | Z = 8 |
| Physical Properties | |
| Mohs hardness | ≈ 4 (VHN 20 = 158 (138-174)) |
| Density (g / cm 3 ) | calculated: 3.29 |
| Cleavage | Please complete |
| colour | orange-red, dark purple to dark red ( scarlet red ) |
| Line color | dark vermilion |
| transparency | translucent to opaque |
| shine | Diamond gloss to semi-metallic gloss |
Fettelite is a mineral from the mineral class of " sulfides and sulfosalts ". It crystallizes in the monoclinic crystal system with the composition Ag 24 HgAs 5 S 20 , so it is chemically a silver - mercury - sulfosalt.
Fettelite is translucent to opaque and usually develops pseudo-hexagonal tablets and flakes up to about 0.2 millimeters in size, which are often arranged in parallel or rosette-shaped aggregates . The color of the diamond to semi-metallic shiny crystals varies between orange-red and dark purple to dark red (also scarlet red ). The streak color is described as dark vermilion.
Etymology and history
Fettelite was first discovered in a quarry on Glasberg near Nieder-Beerbach in the Hessian Odenwald . It was scientifically described in 1996 by N. Wang and A. Paniagua, who named the mineral after its discoverer M. Fettel.
classification
In the now outdated, but still in use, 8th edition of the mineral classification according to Strunz , the fettelite belonged to the general section of "sulfosalts", where it formed the unnamed group II / E.06 together with arcubisite , selenostephanite and stephanite .
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 fettelite in the more finely subdivided section of "unclassified sulfosalts". This section is further subdivided according to the possible presence of lead (Pb) in the formula, so that the mineral can be found according to its composition in the sub-section "without Pb", where it is the only member of the unnamed group 2.LA.30 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , classifies the fettelite in the “sulfosalts” division. Here he is together with Arcubisit in the unnamed group 02/03/06 within the subsection “ 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 ”.
Crystal structure
Fettelite crystallizes monoclinically in space group C 2 (space group no. 5) with the lattice parameters a = 26.030 Å , b = 15.059 Å, c = 15.524 Å and β = 90.45 ° and 8 formula units per unit cell .
Education and Locations
Fettelite forms in low grade, hydrothermal Prehnit - calcite - quartz - veins . As Begleitminerale occur among other Cinnabarit , safflorite , dignified silver and various silver Sulfides and -Sulfosalzen as Proustite , Pearceit and Xanthokon on.
As a rare mineral formation, so far (as of 2012) fettelite could only be detected at a few sites. In addition to its type locality Glasberg near Nieder-Beerbach , the mineral also occurred in Germany in the hydrothermal vein deposit between Schlema, Alberoda and Hartenstein (or Schneeberg, see also deposit description at SDAG Wismut ).
In Chile, fettelite was found in several mines near the mining village of Chañarcillo in the Atacama region and in Morocco it was found in the “Imiter” mine near Djebel Sarhro in the Souss-Massa-Draâ region.
See also
literature
- N. Wang, A. Paniagua: Fettelite, a new Hg-sulfosalt mineral from Odenwald , in: New year book for mineralogy , monthly books (1996), pp. 313-320
- Luca Bindi, Frank N. Keutsch, Carl A. Francis, Silvio Menchetti: Fettelite, [Ag 6 As 2 S 7 ] [Ag 10 HgAs 2 S 8 ] from Chañarcillo, Chile: Crystal structure, pseudosymmetry, twinning, and revised chemical formula , in: American Mineralogist , Volume 94 (2009), pp. 609–615 ( PDF 2.56 MB )
Web links
Individual evidence
- ↑ a b c Webmineral - Fettelite
- ↑ a b c American-Mineralogist-Crystal-Structure-Database - Fettelite (2012)
- ↑ a b c John L. Jambor, Jacek Puziewicz, Andrew C. Roberts: New Mineral Names , in: American Mineralogist , Volume 82 (1997), pp. 620-624 ( PDF 78.8 kB ; Fettelite p. 2)
- ^ 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. 127 .
- ↑ a b John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols: Fettelite , in: Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 61.5 kB )
- ^ Mineralienatlas: List of the localities for Fettelite
- ↑ Mindat - Fettelite