Auricupride
| Auricupride | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula | Cu 3 Au (also AuCu 3 ) |
|
Mineral class (and possibly department) |
Elements - metals and intermetallic compounds |
|
System no. to Strunz and to Dana |
1.AA.10a ( 8th edition : I / A.01) 01.01.02.01 |
| Crystallographic Data | |
| Crystal system | cubic |
| Crystal class ; symbol | cubic hexakisoctahedral; 4 / m 3 2 / m |
| Space group | Pm 3 m (No. 221) |
| Lattice parameters | a = 3.75 Å |
| Formula units | Z = 1 |
| Physical Properties | |
| Mohs hardness | 3 to 3.5 |
| Density (g / cm 3 ) | measured: 11.5; calculated: [13.77] |
| Cleavage | is missing |
| colour | bronze yellow, copper red |
| Line color | copper |
| transparency | opaque |
| shine | strong metallic luster |
Auricuprid , also gold cuprid or cuproaurite , is a rarely occurring mineral from the mineral class of the "elements (including natural alloys, intermetallic compounds, carbides, nitrides, phosphides and silicides)" with the idealized chemical composition Cu 3 Au and is therefore chemically natural Alloy of copper and gold with a molar ratio of 3: 1.
Auricuprid crystallizes in the cubic crystal system and forms massive, very thin, flat aggregates up to about 100 μm in size from bronze-yellow to copper-red in color. The mineral appears pink-violet in reflected light microscopy .
Etymology and history
The mineral is named after the Latin names of the elements involved, aurum for gold and cuprum for copper .
Natural mineral formation auricupride was first in the gold - deposit Zolotaya Gora ( "Gold Mountain"), more precisely in the later as "Mine No. 9 ”was discovered between the Alekseevskii and Novyi gorges on the Karabasch ridge near the city of the same name in the Russian Oblast of Chelyabinsk (southern Urals). The first description of this deposit and the copper-colored gold was already in 1908 by A. Nikolaev. An exact mineralogical description of the copper gold from Karabasch followed in 1935 and 1939 by MP Lozhechkin, who is considered the discoverer of the mineral and suggested the name Cuproaurid for the new mineral. KA Nenadkevich determined a first chemical composition of the mineral with a proportion of 74.33% by weight gold, 20.39% by weight copper and a smaller proportion of up to 4.49% by weight silver, with silver-containing auricuprides meanwhile be regarded as a variety ( argentocuproaurid ). According to more recent analyzes, the adjusted, idealized chemical composition is Cu 3 Au.
The compound Cu 3 Au was known as a synthetic product even before the mineral was first described. The name proposed by Lozhechkin was changed to Auricuprid in 1950 by Paul Ramdohr .
classification
Already in the outdated, but still in use 8th edition of the mineral systematics according to Strunz , the auricuprid belonged to the mineral class of the "elements" and there to the department of "metals and intermetallic alloys (without semi-metals)", where together with Anyuiit , Bogdanovit , gold , Hunchunit , copper , novodneprite , silver , tetra-auricuprid 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 classifies auricuprid into the department of “Metals and Intermetallic Compounds”. 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. Auricuprid can be found here according to its composition in the subdivision "Copper Cupalite Family", where it is the only member of the unnamed group 1.AA.10a .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the auricuprid to the class and there in the department of the same name of "elements". Here he is together with Tetra-Auricuprid and Yuanjiangit in the " Auricupridgruppe " with the system no. 01.01.02 to be found in the subsection "Elements: Metallic elements other than the platinum group".
Crystal structure
Aurocuprid crystallizes in the cubic crystal system with the space group Pm 3 m (space group no. 221) with the lattice parameter a = 3.75 Å and one formula unit per unit cell .
The crystal structure consists of cube-shaped unit cells with the closest cubic packing of spheres , which corresponds to a face-centered cubic lattice. Each gold atom is surrounded by 12 copper atoms as direct neighbors or each copper atom is surrounded by 4 gold and 8 copper atoms.
properties
Auricuprid ( Goldcuprid ) is significantly darker than gold, which can also be seen well on mineral samples, as it often occurs in association with gold. In oil, Auricuprid also reflects the light with a striking pink-violet hue. Auricuprid is just as resistant to weathering and tarnishing caused by surface oxidation as gold.
Auricuprid has a higher hardness than pure or silver-containing gold and is therefore less deformed into thin flakes during transport to the soap deposits.
Modifications and varieties
Auricuprid forms two varieties , the argentocuproaurid and the rozhkovite . Argentocuproaurid contains silver in addition to gold and copper . The palladium-containing variety Rozhkovit was regarded as an independent mineral until it was discredited by the IMA in 2006.
Education and Locations
Auricuprid forms at low temperatures through the order and separation of copper-gold alloys in serpentinites , where it occurs, among other things, in paragenesis with gold, copper and other gold-copper alloys.
As a rare mineral formation, Auricuprid could only be detected at a few sites, whereby around 20 sites have been documented worldwide (as of 2018).
In addition to its type locality Zlatoya Gora in the Urals, Auricuprid was also able to operate in Russia in the Kondjor massif in the Khabarovsk region and in the Aldan highlands in the Sakha Republic and near Pavlovsk near Lake Khanka in the Primorye region in the Far East federal district, in the Talnach copper-nickel deposit can be found near Norilsk in the Eastern Siberia region and on the island of Alexandraland in northwestern Russia.
The only known site in Switzerland so far is Weierfeld in the Rheinfelden district (Canton Aargau).
Other previously known sites are Cajoncillo near Alemanía in the Argentine province of Salta, on the Wilson River on the Australian island of Tasmania , the El Indio copper and precious metal deposit in the Elqui province ( Región de Coquimbo ) in Chile, the area around Korydallos in the Pindos Mountains in the Greek region of Epirus , Novodneprovsk on the field Aqmola Kazakhstan, Jidoştiţa in county Mehedinti and Valea lui Stan in county Valcea in Romania, Borovec at Svratkou nad Štěpánov in the Czech region of Moravia, the open pit Sandsloot in the Limpopo province and the platinum Mooihoek iron-magnesium deposit (Mooihoek Farm) in Mpumalanga Province in South Africa, Pefkos in Limassol District and Laksia in Nicosia District in Cyprus.
See also
literature
- MP Lozhechkin: The Karabash Deposit of copper-bearing gold . In: Tr. Ural'skogo filiala AN SSSR (Proceedings of the Ural Division of RAS) . tape 4 , 1935, pp. 35-45 .
- MP Lozhechkin: New data on chemical composition of "copper-bearing gold" . In: Doklady Academii Nauk SSSR . tape 24 , 1939, pp. 454-457 .
- Michael Fleischer , Louis J. Cabri, Ernest H. Nickel , Adolf Pabst : New Mineral Names . In: American Mineralogist . tape 62 , 1977, pp. 593–600 ( minsocam.org [PDF; 890 kB ; accessed on February 19, 2018] Rozhkovite = palladian cuproauride).
Web links
- Mineral Atlas: Auricuprid (wiki)
- Mindat - Auricupride
- Webmineral - Auricupride
- American-Mineralogist-Crystal-Structure-Database - Auricupride
Individual evidence
- ↑ a b c d Paul Ramdohr : The ore minerals and their adhesions . 4th, revised and expanded edition. Akademie-Verlag, Berlin 1975, p. 363-365 .
- ^ A b Igor V. Pekov: Minerals first discovered on the territory of the former Soviet Union . 1st edition. Ocean Pictures, Moscow 1998, ISBN 5-900395-16-2 , pp. 32-33 .
- ^ A b 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 c d 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 .
- ↑ Aurocupride . 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; 60 kB ; accessed on February 19, 2018]).
- ^ Paul Ramdohr : New ore minerals . In: Advances in Mineralogy . tape 28 , 1950, pp. 69-70 .
- ↑ Mindat - Argentocuproaurid
- ↑ Mindat - Rozhkovit
- ↑ Mindat - Number of localities for Auricuprid
- ↑ a b List of locations for auricuprid in the Mineralienatlas and Mindat