Ferrokerite
| Ferrokerite | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula | Cu 2 (Fe, Zn) SnS 4 |
|
Mineral class (and possibly department) |
Sulfides and sulfosalts |
|
System no. to Strunz and to Dana |
2.CB.15a ( 8th edition : II / C.06) 02.09.02.10 |
| Crystallographic Data | |
| Crystal system | tetragonal |
| Crystal class ; symbol | tetragonal-scalenohedral; 4 2 m |
| Space group | I 4 (No. 82) |
| Lattice parameters | a = 5.43 Å ; c = 10.88 Å |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | ≈4 |
| Density (g / cm 3 ) | calculated: 4.490 |
| Cleavage | clearly after {110} |
| colour | steel gray |
| Line color | black |
| transparency | opaque |
| shine | Metallic luster |
Ferrokësterite is a very rarely occurring mineral from the mineral class of " sulfides and sulfosalts " with the chemical composition Cu 2 (Fe, Zn) SnS 4 . From a chemical point of view, it is therefore a copper - iron - zinc - tin sulfide, whereby the elements iron and zinc indicated in the round brackets can represent each other in the formula ( substitution , diadochie), but always in the same proportion to the other components of the mineral.
Ferrokësterite crystallizes in the tetragonal crystal system and develops only opaque, granular to massive mineral aggregates of steel-gray color with black streak color .
Ferrokësterite is the iron analogue of kësterite and forms a complete mixed crystal row with it .
Etymology and history
Ferrokësterite was discovered for the first time in the "Cligga" mine near St Agnes in the English county of Cornwall and was described in 1989 by Stephen A. Kissin and De Alton R. Owens, who found the mineral after its close relationship with kësterite and the higher iron content ( Greco-Latin prefix ferro ).
Type material of the mineral was deposited in the Geological Survey of Canada in Ottawa (register no. 14747, 65048) and in the Natural History Museum in London (register no. 1984,844).
As early as 1955, an unknown mineral was found in the “Cligga” mine and briefly described under the name isostannite without giving any further information on physical or chemical data. Claringbull and Hey thought the mineral was a form of stannite, but with a cubic structure. During the examination by Kissin and Owens, however, it was found that it was kësterite and ferrokësterite, respectively. Hence the mineral name isostannite has been discredited.
classification
Already in the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the ferrokësterite belonged to the mineral class of "sulfides and sulfosalts" and there to the department of "sulfides with the molar ratio of metal: sulfur, selenium, tellurium ≈ 1: 1", where together with barquillite , briartite , černýite , famatinite , hocartite , kësterite, kuramite , luzonite , permingeatite , petrukite , pirquitasite , rhodostannite , sakuraiite , stannite , toyohaite and velikite the " stannite group " with the system no. II / C.06 formed.
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 assigns ferrokësterite to the class of "sulfides and sulfosalts" and there in the department of "metal sulfides, M: S = 1: 1 (and similar) ”. However, this section is further subdivided according to the predominant metals in the compound, so that the mineral can be found in the sub-section "with zinc (Zn), iron (Fe), copper (Cu), silver (Ag) etc." according to its composition is, where together with Černýit, Hocartit, Idait , Kësterit, Kuramit, Pirquitasit, Stannit and Velikit the "stannite group" with the system no. 2.CB.15a forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns ferrokësterite to the class of "sulfides and sulfosalts" and there to the "sulfide minerals" category. Here he is together with Stannit, Černýit, Briartit, Kuramit, Sakuraiit, Hocartit, Pirquitasit, Velikit, Kësterit and Barquillit in the "Stannite group (tetragonal: I 4 2 m ) A 2 BCS type" with the system no. 02.09.02 within the subsection " Sulphides - including selenides and tellurides - with the composition A m B n X p , with (m + n): p = 1: 1 ".
Crystal structure
Ferrokësterite crystallizes tetragonally in the space group I 4 (space group no. 82) with the lattice parameters a = 5.43 Å and c = 10.88 Å as well as 2 formula units per unit cell .
Modifications and varieties
The compound Cu 2 (Fe, Zn) SnS 4 is dimorphic , so it occurs in nature in addition to the tetragonally crystallizing ferrokesterite as also tetragonal, but in a different space group crystallizing stannite .
Education and Locations
Ferrokësterite is formed in sulphide veins in granite that are bordered by old men . As Begleitminerale occur among other arsenopyrite , chalcopyrite , chalcocite , cassiterite , quartz , sphalerite on.
As a rare mineral formation, ferrokësterite has so far (as of 2012) only been detected at a few sites, its type locality "Cligga Mine" near St Agnes being the only known site in the United Kingdom to date.
Other sites include the "Oploca" mine near Pirquitas in the Rinconada department and the "Pingüino deposit " ( Cerro León ) near Macizo del Deseado in Santa Cruz in Argentina, the "Itos" and "San José" mines near Oruro in Brazil, the "Yaogangxian" mine in the same tungsten-tin ore field of Yizhang in China and in the dolomite - quarry at Rędziny on Landeshuter comb in Poland.
See also
literature
- Stephen A. Kissin, De Alton R. Owens: The relatives of stannite in the light of new data , in: Canadian Mineralogist , Volume 27 (1989), pp. 673–688 ( PDF 2.74 MB )
Web links
- Mineral Atlas: Ferrokësterite (Wiki)
- Database-of-Raman-spectroscopy - ferrokesterites or ferrokesterites
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. 78 .
- ↑ Webmineral - Ferrokësterite
- ↑ a b c d John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols: Ferrokësterite , in: Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 59.6 kB )
- ↑ a b Kissin, Owens: The relatives of stannite in the light of new data (see literature)
- ↑ Mindat - Ferrokësterite