Skutterudit
| Skutterudit | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula | CoAs 3 |
|
Mineral class (and possibly department) |
Sulphides, sulphosalts - metal: sulfur, selenium, tellurium <1: 1 |
|
System no. to Strunz and to Dana |
2.EC.05 ( 8th edition : II / D.29) 02.12.17.01 |
| Similar minerals | Nickel cutter audit |
| Crystallographic Data | |
| Crystal system | cubic |
| Crystal class ; symbol | cubic-disdodecahedral; 2 / m 3 |
| Space group | Im 3 (No. 204) |
| Lattice parameters | a = 8.31 Å |
| Formula units | Z = 8 |
| Twinning | Sextuplets according to {112} |
| Physical Properties | |
| Mohs hardness | measured: 6 |
| Density (g / cm 3 ) | measured: 6.5; calculated: 6.821 |
| Cleavage | clearly after {001} and {111} |
| Break ; Tenacity | shell-like to uneven |
| colour | tin white to silver gray, gray or iridescent tapering |
| Line color | black |
| transparency | opaque |
| shine | Metallic luster |
Skutterudite is a rather seldom occurring mineral from the mineral class of " sulfides and sulfosalts " with the idealized composition CoAs 3 and is chemically a cobalt arsenide related to sulfides . Since Skutterudit however closely with Nickelskutterudit ((Ni, Co, Fe) As 3-x is used), and with this a complete mixed crystal forms series, he usually also contains some nickel and iron , which the cobalt diadoch can replace.
Skutterudite crystallizes in the cubic crystal system and develops mostly cubic, octahedral or dodecahedral crystals and combinations of up to 9 cm in size, but can also be found in the form of granular, massive, dendritic or skeletal aggregates . The surfaces of the opaque crystals and aggregates have a metallic sheen . The color of fresh skutterudite varies from pewter white to silver gray. When exposed to air, however, it turns gray to brightly iridescent after a while .
Etymology and history
Skutterudit had been known under its mining name Speiskobalt since the Middle Ages, as it was used for the production of " smalt ". Abraham Gottlob Werner adopted this name in 1803 in his "Handbuch der Mineralogie". According to Johann Christoph Adelung, the word Speis (from food ) was used in mining and metallurgy to denote, among other things, metallic mixtures with an unknown composition (e.g. bell food ).
Because of its intended use, the French mineralogist François Sulpice Beudant recorded the Arséniure de cobalt as Smaltine (occasionally also smaltite ) in his "Traité élémentaire de minéralogie" in 1832.
The mineral's name, which is still valid today, skutterudite was finally given in 1845 by Wilhelm Ritter von Haidinger , who named it after its type locality , the cobalt mines of Skutterud near Snarum and Modum in Norway .
classification
Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , skutterudite belonged to the mineral class of "sulphides and sulphosalts" and there to the department of "sulphides with the molar ratio metal: sulfur, selenium, tellurium <1: 1" he together with Ferroskutterudit , Gaotaiit , Kieftit and Nickelskutterudit the unnamed group II / D.29 formed.
In contrast , 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 skutterudite under the category of “metal sulfides with M: S ≤ 1: 2”. This is further subdivided according to the exact molar ratio or the predominant metals in the compound, so that the mineral can be found according to its composition in the sub-section "M: S = 1:> 2", where it can be found together with Ferroskutterudit, Kieftit and Nickelskutterudit the "Skutteruditgruppe" with the system no. 2.EC.05 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the skutterudite to the class of "sulfides and sulfosalts" and there to the department of "sulfide minerals". Here he is together with Kieftit, Ferroskutterudit and Nickelskutterudit in the " Skutterudit series " with the system no. 02.12.17 to be found within the subsection of "Sulphides - including selenides and tellurides - with the composition A m B n X p , with (m + n): p = 1: 2".
Crystal structure
Skutterudite crystallizes cubically in the space group Im 3 (space group no. 204) with the lattice parameter a = 8.31 Å and 8 formula units per unit cell .
Modifications and varieties
In addition to its original meaning as a synonym for skutterudite, the name smaltin or smaltite is now also used as a name for a variety of the mineral that is poor in arsenic.
Edible cobalt is also found coarse, broken in and in variously grouped aggregates, is tin-white to gray, sometimes tarnished or colored red on the surface due to the beginning of decomposition into cobalt bloom .
In certain varieties, the content of nickel becomes so significant that they are more likely to be attributed to the nickel cutter audit , while the iron-rich varieties are more likely to be considered varieties of safflorite (outdated: gray cobalt , iron cobalt gravel ). A mineral containing up to 4 percent bismuth (bismuth) is differentiated as bismuth cobalt gravel .
Education and Locations
Skutterudit forms in medium to high grade hydrothermal - veins , where he met mostly with other nickel-cobalt sulphides such as Nickelin , cobaltite and arsenopyrite , but also with native bismuth and silver , barite , calcite , quartz and / or siderite associated encountered is.
As a rather rare mineral formation, skutterudite can sometimes be abundant at various locations, but overall it is not very common. A little more than 400 sites are known to date (as of 2011). In addition to its type locality Skutterud, the mineral has so far appeared in Norway in the "Lerestvedt Mine" near Øyestad in the Arendal municipality and in the silver mining area around Kongsberg .
In Germany, skutterudit has so far mainly been found in the Black Forest in Baden-Württemberg and in the Ore Mountains in Saxony, but also in several places in Franconia and near Wölsendorf in Bavaria, in several pits in the Odenwald and in the Richelsdorf mountains in Hesse, in many places in the Harz Mountains from Lower Saxony to Saxony-Anhalt, in the Bergisches Land and Siegerland in North Rhine-Westphalia, at several sites near Imsbach , on Landsberg near Obermoschel , Rockenhausen and Bürdenbach in Rhineland-Palatinate and in Thuringia near Bad Lobenstein , Ronneburg and Kamsdorf .
In Austria, the mineral has so far been found on the Hüttenberger Erzberg in Carinthia, the zinc wall in the valley of the Obertalbach ( Schladminger Tauern ) in Styria and in several places in Salzburg .
So far, only Böttstein in the canton of Aargau and various pits in the Ayertal and the municipality of Turtmann in the canton of Valais are known to have been found in Switzerland.
Other locations are in Afghanistan, Argentina, Australia, Bolivia, Chile, China, France, Greenland, Ireland, Italy, Japan, Canada, Madagascar, Morocco, Mexico, Poland, Portugal, Russia, Sweden, Slovakia, Spain, South Africa, South Korea, the Czech Republic, the United Kingdom (Great Britain) and the United States (USA).
use
Until the end of the 19th century, skutterudite was an important cobalt and nickel ore for blue color processing, with nickel and white arsenic (III) oxide (arsenic) being obtained as a by-product. These metals are now mainly extracted from nickel magnetic gravel (a mixture of pentlandite and pyrrhotite ) and laterites .
Skutterudites are traded as candidates for more efficient thermoelectric converters , with which, for example, heat in the exhaust system of a car can be converted directly into electricity, but there are considerable technical problems in the way. In the meantime, skutterudites are being tested as materials for radioisotope generators in space travel.
See also
literature
- Martin Okrusch, Siegfried Matthes: Mineralogy. An introduction to special mineralogy, petrology and geology . 7th fully revised and updated edition. Springer Verlag, Berlin et al. 2005, ISBN 3-540-23812-3 , pp. 41 .
- Petr Korbel, Milan Novák: Encyclopedia of Minerals . Dörfler Verlag GmbH, Eggolsheim 2002, ISBN 978-3-89555-076-8 , p. 48 .
Web links
- Mineral Atlas: Skutterudite (Wiki)
- Webmineral - Skutterudite (English)
- RRUFF Database-of-Raman-spectroscopy - Skutterudite
Individual evidence
- ↑ a b c d e Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 109 .
- ↑ a b c d John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols: Skutterudite , in: Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 65.3 kB )
- ↑ Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 , p. 333-334 .
- ↑ Handbook of Mineralogy according to AG Werner in the Google book search
- ↑ Hans Lüschen: The names of the stones. The mineral kingdom in the mirror of language . 2nd Edition. Ott Verlag, Thun 1979, ISBN 3-7225-6265-1 , p. 324 .
- ↑ Traité élémentaire de minéralogie , Volume 2 by François Sulpice Beudant in the Google book search
- ^ Wilhelm Haidinger: Second class: Geogenide. XIII. Order. Kiese III. Cobalt gravel. Skutterudit , in: Handbook of Determining Mineralogy , Bei Braumüller and Seidel, Vienna 1845, pp. 559–562 ( PDF 239.5 kB )
- ↑ Mindat - Smaltite
- ↑ Meyers Konversationslexikon - Speiskobalt and bismuth cobalt gravel
- ^ Mindat - Skutterudite
- ↑ Mindat - Localities for Skutterudites
- ↑ Thermoelectric converters - Skutterudite (English)
- ↑ Technology Review: Much too hot sled . Report on approaches in industrial research. Retrieved May 31, 2011.
- ↑ Tony Greicius: Spacecraft 'Nuclear Batteries' Could Get a Boost from New Materials . In: NASA . October 12, 2016 ( nasa.gov [accessed June 3, 2017]).