Tetra-auricupride
| Tetra-auricupride | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula | CuAu |
|
Mineral class (and possibly department) |
elements |
|
System no. to Strunz and to Dana |
1.AA.10b ( 8th edition : I / A.01) 01.01.02.02 |
| Crystallographic Data | |
| Crystal system | tetragonal |
| Crystal class ; symbol | ditetragonal-dipyramidal; 4 / m 2 / m 2 / m |
| Space group | P 4 / mmm (No. 123) |
| Lattice parameters | a = 2.81 Å ; c = 3.72 Å |
| Formula units | Z = 1 |
| Physical Properties | |
| Mohs hardness | 3.5 to 4 (VHN 5 : 344, VHN 10 : 288, VHN 20 : 294) |
| Density (g / cm 3 ) | calculated: 14.67 |
| Cleavage | no |
| Break ; Tenacity | plastically deformable |
| colour | golden yellow to copper red with a yellow tinge |
| Line color | not defined |
| transparency | opaque |
| shine | strong metallic luster |
| Other properties | |
| Chemical behavior | insoluble in hydrochloric, sulfuric and nitric acid |
Tetra-Auricuprid (also Tetraauricuprid ) is a rarely occurring mineral from the mineral class of the "elements" with the chemical composition CuAu. The mineral consists of copper and gold in a 1: 1 ratio, which form a natural alloy .
Tetra-Auricuprid does not crystallize like the pure metals copper and gold in the cubic , but in the tetragonal crystal system . This phenomenon is also known as the intermetallic compound . So far, tetra-auricupride has only been found in nature in the form of irregular, striped grains of up to 600 μm in size. The mineral is opaque in every form, from golden yellow to copper red in color with a tinge of yellow and has a strong metallic sheen .
Etymology and history
Tetra-Auricuprid was first discovered in 1982 in a platinum-metal-containing , basic to ultra-basic stick near Sardala in Manas County (Xinjiang Autonomous Region) in the People's Republic of China. The mineral was described by Chen Keqiao, Yu Tinggao, Zhang Yongge and Peng Zhizhong, who named it based on its tetragonal symmetry, which is in contrast to the chemically similar but cubic auricupride .
In the first description, the mineral name was published in the spelling Tetraauricuprid . With the 2008 publication "Tidying up Mineral Names: an IMA-CNMNC Scheme for Suffixes, Hyphens and Diacritical marks", this spelling was officially corrected to Tetra-Auricuprid in order to prevent possible problems with the deciphering of the name. Occasionally, however, this corrected spelling can also be found in older sources.
Type material of the mineral is in China geological museum in Beijing ( Beijing kept).
classification
In the outdated, but partly still in use, 8th edition of the mineral classification according to Strunz , the tetra-auricuprid belonged to the mineral class of the "elements" and there to the department of "metals and intermetallic alloys (without semimetals)", where together with Anyuiit , auricuprid , Bogdanovite , gold , hunchunite , copper , novodneprite , silver and yuanjiangite the "copper series" with the system no. I / A.01 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 tetra-auricuprid to the "Metals and Intermetallic Compounds" section. However, this is further subdivided according to the predominant metals in the compound, which have been divided into metal families according to their related properties. Tetra-Auricuprid can be found here according to its composition in the sub-section "Copper Cupalite Family", where it forms the unnamed group 1.AA.10b as the only member .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns tetra-auricuprid to the class of "elements" and there to the department of the same name. Here he is together with Auricuprid and Yuanjiangit in the " Auricuprid group " with system no. 01.01.02 to be found in the subsection "Elements: Metallic elements other than the platinum group".
Chemism
The quantitative analysis of the microsamples showed an average weight fraction of 23.74% copper and 75.81% gold. The empirical formula is therefore Cu 0.3736 Au 0.3817 and the idealized formula is CuAu.
The weight proportions of the compound CuAu (260.513 u) calculated on the basis of the atomic masses of copper (63.546 u) and gold (196.967 u) is, however, 24.39% copper and 75.61% gold.
Crystal structure
Tetra-auricupride crystallizes tetragonally in the space group P 4 / mmm (space group no. 123) with the lattice parameters a = 2.81 Å and c = 3.72 Å and one formula unit per unit cell .
properties
The Mohs hardness of tetra-auricupride is 3.5 to 4, but it can be plastically deformed well.
Tetra-auricupride is not soluble in hydrochloric , sulfuric or nitric acid.
Education and Locations
Tetra-auricupride forms in platinum-metal-containing, mafic to ultramafic rocks . The accompanying minerals include apatite , chalcopyrite , chromite , diopside , epidote , magnetite , pyrite , pyrrhotite , tremolite , zircon , solid gold and silver as well as various minerals of the chlorite , serpentine and platinum group minerals .
As a rare mineral formation, Tetra-Auricuprid could only be detected at a few sites, whereby so far (as of 2017) around 25 sites are known. Its type locality Sardala is the only known site in China so far.
In Europe, the mineral has so far only been found in an alluvial deposit on the Durance in the French region of Provence-Alpes-Côte d'Azur, in the ophiolite complex of the Pindos Mountains in the area around Korydallos in Greece, near Lubin and in the Sieroszowice mine in the Legnicki district in in the Polish Voivodeship of Lower Silesia and in a soap deposit on the Rio de Miséry in the municipality of Grolley in the canton of Friborg and on the Züesee near the Binntaler Geisspfad in the canton of Valais in Switzerland.
Other locations include Brazil, Greenland, Canada (Ontario), Morocco, Pakistan, Russia (northern region, Urals, Eastern Siberia, Far East), South Africa (Limpopo and Mpumalanga) and the United States (Colorado).
See also
literature
- Chen Keqiao, Yu Tinggao, Zhang Yongge, Peng Zhizhong: Tetraauricupride, CuAu discovered in China . In: Chinese Journal of Geology . tape 17 , no. 1 , 1982, pp. 111–116 ( brief description available online at dzkx.org [accessed June 25, 2017]).
- Pete J. Dunn, Michael Fleischer, George Y. Chao, Louis J. Cabri, Joseph A. Mandarino: New Mineral Names . In: American Mineralogist . tape 68 , 1983, pp. 1248–125 ( minsocam.org [PDF; 622 kB ; accessed on June 25, 2017]).
Web links
- Mineral Atlas: Tetra-Auricuprid (Wiki)
- Mindat - Tetra-auricupride (English)
- American-Mineralogist-Crystal-Structure-Database - Tetraauricupride (English)
Individual evidence
- ↑ a b c d 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. 35 .
- ↑ a b Webmineral - Tetra-auricupride (English)
- ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 6th completely revised and supplemented edition. Weise, Munich 2014, ISBN 978-3-921656-80-8 .
- ↑ a b c d Pete J. Dunn, Michael Fleischer, George Y. Chao, Louis J. Cabri, Joseph A. Mandarino: New Mineral Names . In: American Mineralogist . tape 68 , 1983, pp. 1250 ( minsocam.org [PDF; 622 kB ; accessed on June 25, 2017]).
- ↑ a b c Tetra-auricupride . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 58 kB ; accessed on May 19, 2017]).
- ^ Ernst AJ Burke: Tidying up Mineral Names: an IMA-CNMNC Scheme for Suffixes, Hyphens and Diacritical marks . In: Mineralogical Record . tape 39 , no. 2 , March 2008, p. 133 ( edu.au [PDF; 2.8 MB ; accessed on June 25, 2017]).
- ↑ 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. 806 (as tetra-auricupride in the appendix).
- ↑ Chen Keqiao, Yu Tinggao, Zhang Yongge, Peng Zhizhong: Tetraauricupride, CuAu discovered in China . In: Chinese Journal of Geology . tape 17 , no. 1 , 1982, pp. 111–116 ( brief description available online at dzkx.org [accessed June 25, 2017]).
- ↑ Mindat - Number of localities for Tetra-Auricuprid
- ↑ Find location list for tetraauricuprid in the Mineralienatlas and Mindat