Fettelite
- IMA 1994-056
Fettelit is a naturally occurring mineral from the mineral class of " sulfides and sulfosalts ". It crystallizes in the monoclinic crystal system with the composition Ag24HgAs5S20, is so chemically seen a silver-mercury - sulfosalt.
Fettelit is translucent to opaque and usually develops pseudohexagonal tablets and flakes to about 0.2 millimeters in size, which are often arranged in parallel layered or rosette-shaped aggregates. The color of the diamond to semi-metallic shiny crystals varies from orange-red and dark violet to dark red (also scarlet ). The stroke color is described as Dunkelzinnoberrot.
Etymology and history
Was first discovered Fettelit in a quarry on the glass mountain in low - Beersbach in the Hessian Odenwald. He was scientifically described in 1996 by N. Wang and A. Paniagua, designated the mineral after its discoverer M. Fettel.
Classification
In the now outdated but still in use 8th edition of the mineral classification by Strunz the Fettelit belonged to the general ward of " thio ", where he led the unnamed group II/E.06 formed together with Arcubisit, Selenostephanit and stephanite.
The 9th edition valid since 2001 and of the International Mineralogical Association (IMA ) used the Strunz'schen Mineral classification assigns the Fettelit in the fine already divided department of 'unclassified sulfosalts " one. This department is also further divided according to the possible presence of lead ( Pb ) in the formula, so that the mineral is found according to its composition in the subdivision " without Pb", where it is the only member of the unnamed group 2.LA.30 forms.
The mainly common in English-speaking classification of minerals according to Dana assigns the Fettelit in the department of " thio ". Here he is with Arcubisit in the unnamed group 03.02.06 within the subdivision " sulfosalts with the ratio z / y = 4 and the composition (A ) i ( A2 ) j [ Bycz ], A = metals, B = semimetals, C = non-metals to find. "
Education and Locations
Fettelit forms in low-grade hydrothermal prehnite - calcite - quartz veins. Accompanying minerals occur among other Cinnabar, Safflorite, native silver and various silver sulfides or sulfosalts - like Proustite, Pearceit and Xanthokon on.
A rare mineral formation Fettelit previously could (as of 2012) are detected only at a few localities. Except at its type locality Glasberg in low - Beersbach the mineral still occurred in the hydrothermal reservoir transition between Schlema, Alberoda and Hartenstein (or Schneeberg, see also deposit description when Wismut ) in Germany.
In Chile, Fettelit found in several mines near the mining village Chañarcillo in the Atacama region and in Morocco it could be detected in the region of Souss -Massa- Draâ in the mine " Imiter " at Djebel Sarhro.
Crystal structure
Fettelit crystallizes in the monoclinic space group C2 ( Raumgruppen-Nr. 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.