Cubanite
| Cubanite | |
|---|---|
 |
|
| General and classification | |
| chemical formula | CuFe 2 S 3 |
|
Mineral class (and possibly department) |
Sulfides and sulfosalts |
|
System no. to Strunz and to Dana |
2.CB.55a ( 8th edition : II / C.14) 02.09.13.01 |
| Crystallographic Data | |
| Crystal system | orthorhombic (pseudohexagonal) |
| Crystal class ; symbol | orthorhombic-dipyramidal; 2 / m 2 / m 2 / m |
| Space group | Pcmn (No. 62, position 4) |
| Lattice parameters | a = 6.458 (1) Å ; b = 11.104 (1) Å; c = 6.220 (1) Å |
| Formula units | Z = 4 |
| Twinning | often along {110}; Forming twins, quadruplets and sextuplets |
| Physical Properties | |
| Mohs hardness | 3.5 |
| Density (g / cm 3 ) | measured: 4.03 to 4.18; calculated: 4.024 |
| Cleavage | is missing |
| Break ; Tenacity | shell-like |
| colour | brass to bronze colored |
| Line color | black |
| transparency | opaque |
| shine | Metallic luster |
Cubanite , also barracanite or chalmersite , is a seldom occurring mineral from the mineral class of sulfides and sulfosalts . It crystallizes in the orthorhombic crystal system with the chemical composition CuFe 2 S 3 and forms elongated crystals as well as thick, striped sheets of up to three centimeters in size from brass to bronze-like color. Star- or flower-shaped crystal twins that simulate a hexagonal symmetry are also often found.
Etymology and history
Cubanite was first described in 1843 by August Breithaupt , who examined a mineral sample made available to him in more detail. He had brought six barrels of the unknown mineral from Cuba to England to carry out melting tests. Breithaupt named the mineral after its place of origin, the island of Cuba Cubanit .
classification
In the systematics of minerals according to Strunz , cubanite 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 a group together with argentopyrite , enargite , sternbergite and stibioenargite . In the 9th edition it forms with isocubanite a subgroup of the sulfides with zinc , iron , copper or silver .
In the Dana systematics, argentopyrite and isocubanite form a subgroup of sulphides, selenides and tellurides with the composition A m B n X p , with (m + n): p = 1: 1.
Crystal structure
Cubanite crystallizes orthorhombically in the space group Pcmn (space group no.62 , position 4) with the lattice parameters a = 6.458 (1) Å , b = 11.104 (1) Å and c = 6.220 (1) Å as well as four formula units per unit cell .
properties
In the structure, the metal ions are in different oxidation states. The copper is monovalent and there are both divalent and trivalent iron ions in the lattice. These are each in pairs in tetrahedra , which are connected to one another via common edges. This leads to rapid electron transfers between the iron ions. This makes the mineral a semiconductor . At the same time, cubanite is strongly magnetic in the direction of the c-axis .
Modifications and varieties
Above 210 ° C the crystal structure of the cubanite changes. A cubic modification is formed called isocubanite , which also occurs naturally. Isocubanite can usually be found near black smokers , for example in the Pacific .
Two high pressure modifications are also known. At 3.3 GPa pressure, cubanite transforms into a hexagonal modification at room temperature. Their structure is comparable to the nickel arsenide structure . At even higher pressures of 3.4 to 5.8 GPa, the properties of the cubanite change significantly and a metallic modification is formed.
Education and Locations
Cubanite is formed under hydrothermal conditions at higher temperatures in pyrrhotite - pentlandite ores. It is formed by segregation of chalcopyrite , with which it is often strongly fused, at 200–210 ° C. It is associated with chalcopyrite, pyrite , pyrrhotite, pentlandite and sphalerite .
So far (as of 2009), Cubanite has been detected at around 480 sites around the world, where it also occurs locally in large quantities. The locations include the type locality Barracanao in Cuba, Sudbury and Chibougamau in Canada , Tunaberg and Ljusnarsberg in Sweden , Virtasalm in Finland , Traversella in Italy , Nova Lima in Brazil , Broken Hill in Australia , Norilsk in Russia and the US states New Mexico , Arizona and Alaska .
Cubanite is also rarely found in carbonaceous chondrites , a type of meteorite.
use
If cubanite is locally available in large quantities, for example in Ontario in Canada, it is mined as copper ore for the extraction of elemental copper.
See also
literature
- Cubanit in: Anthony et al .: Handbook of Mineralogy , 1990, 1, 101 ( pdf ).
- Entry on Cubanite. In: Römpp Online . Georg Thieme Verlag, accessed on January 2, 2015.
- Petr Korbel, Milan Novák: Encyclopedia of Minerals . Dörfler Verlag GmbH, Eggolsheim 2002, ISBN 978-3-89555-076-8 , p. 31 .
Web links
- Mineral Atlas: Cubanite (Wiki)
- Mindat - Cubanite (English)
Individual evidence
- ↑ Webmineral - Cubanite (English)
- ↑ a b c Catherine McCammon, Jinmin Zhang, Robert M. Hazen, Larry W. Finger: High-pressure crystal chemistry of cubanite, CuFe 2 S 3 . In: American Mineralogist. 1992, Volume 77, pp. 937-944 ( pdf )
- ↑ a b c d Cubanite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 62.3 kB )
- ↑ Mineralien-Lexikon - Cubanit ( Memento of the original from January 28, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ August Breithaupt: Cuban, a new gravel similar to white copper ore. In: Annals of Physics . 1843, 135, 6, pp. 325-327, doi : 10.1002 / andp.18431350610
- ^ Friedrich Klockmann : Klockmanns textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 438 (first edition: 1891).
- ↑ a b c Eckard Amelingmeier: Cubanite . In: Römpp Chemistry Lexicon. Thieme Verlag, as of August 2004.
- ↑ Mindat - Localities for Cubanite
