Villamanínit
| Villamanínit | |
|---|---|
 |
|
| General and classification | |
| chemical formula |
|
|
Mineral class (and possibly department) |
Sulfides and sulfosalts |
|
System no. to Strunz and to Dana |
2.EB.05a ( 8th edition : II / C.05) 02.12.01.06 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic sphenoid; 2 |
| Space group | P 2 1 (No. 4) |
| Lattice parameters |
a = 5.704-5.709 Å ; b = 5.703-5.707 Å; c = 5.704-5.708 Å, β = 89.99-90.01 ° |
| Physical Properties | |
| Mohs hardness | 4.5 (VHN 20 = 535–710 for spherical aggregates; 440–520 for idiomorphic crystals) |
| Density (g / cm 3 ) | measured: 4.4 to 4.5; calculated: 4.408 to 4.604 |
| Cleavage | perfectly |
| Break ; Tenacity | uneven; brittle |
| colour | Iron black |
| Line color | Soot black |
| transparency | opaque (opaque) |
| shine | Metal gloss, matt |
Villamanínit is a rarely occurring mineral from the mineral class of "sulphides and sulphosalts" with the idealized chemical composition CuS 2 and thus, chemically speaking, copper (II) disulphide .
In the case of naturally occurring Villamanínites, however, some of the copper can be replaced ( substituted ) by nickel , cobalt and / or iron and some of the sulfur by selenium , which is why the formula is also used in various sources with (Cu, Ni, Co, Fe) ( S, Se) 2 indicated.
Villamanínite crystallizes in the monoclinic crystal system and develops mostly small, pseudocubic crystals (including cuboctahedra ) with curved crystal faces up to about five millimeters in length, but also occurs in the form of spherical or grape mineral aggregates with a radial structure. The mineral is in any form opaque ( opaque ) and of predominantly iron black color in pitch black line color , but shows on polished surfaces has a rather bright blue-gray to violet gray reflection color.
Etymology and history
The mineral was first discovered in the Mina La Divina Providencia about six kilometers east-northeast of the municipality of Villamanín ( Cármenes ) in the Spanish province of León . It was first described in 1919 by WR Schoeller and AR Powell, who named the mineral after its type locality .
The type material of the mineral is in the Natural History Museum in London (United Kingdom) under the catalog no. 1919,309 and 1920,7 kept.
classification
Already in the outdated 8th edition of the mineral classification according to Strunz , the villamanínite belonged to the mineral class of "sulfides and sulfosalts" and there to the division of "sulfides with (the molar ratio ) M (metal): S (sulfur) <1: 1", where together with Aurostibit , Cattierit , Geversit , Hauerit , Laurit , Michenerit , Penroseit , Pyrite , Sperrylite , Trogtalit and Vaesit the “Pyrite series” with the system no. II / C.05 formed.
In the Lapis mineral directory according to Stefan Weiß, which, out of consideration for private collectors and institutional collections, is still based on this old form of Karl Hugo Strunz's system , the mineral was given the system and mineral number. II / D.17-20 . In the "Lapis system" this also corresponds to the section "Sulphides with the molar ratio of metal: S, Se, Te <1: 1", where Villamanínit together with Aurostibit, Cattierit, Changchengit , Dzharkenit , Erlichmanit , Fukuchilit , Geversit, Hauerit, Insizwait , Krutaite , Laurit, Maslovit , Mayingit , Michenerit, Padmait , Penroseite, pyrite, Sperrylith, Trogtalit, Testibiopalladit and Vaesit the "pyrite group" formed (as 2018).
The 9th edition of Strunz's mineral systematics, valid since 2001 and updated by the International Mineralogical Association (IMA) until 2009, classifies the Villamanínit in the department of "Metal sulfides with M: S ≤ 1: 2". This is further subdivided according to the exact molar ratio and 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, with Fe, Co, Ni, PGE etc.", where it together with Aurostibit, cattierite, Dzharkenit, Erlichmanit, Fukuchilit, Gaotaiit , Geversit, Hauerit, Insizwait, Iridisit , Krutaite, Laurit, Penroseite, pyrite, Sperrylith, Trogtalit and Vaesit the "pyrite group" with the system number. 2.EB.05a forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Villamanínit to the class of "sulfides and sulfosalts" and there in the department of "sulfide minerals". Here he is the only member / together with the " Pyrite group (isometric: Pa3) " with the system no. 02.12.01 to be found within the subsection “Sulphides - including selenides and tellurides - with the composition A m B n X p , with (m + n): p = 1: 2”.
Chemism
According to the idealized (theoretical) composition of Villamanínit (CuS 2 ), which is also specified by the IMA, the mineral consists of copper (Cu) and sulfur (S) in a molar ratio of 1: 2, which is a mass fraction (% by weight) of 49.78% Cu and 50.22% S.
Several analyzes on the type material from Spain, carried out by Schoeller and Powel in 1919 on hand-picked and acid-cleaned granular and crystalline samples, resulted in a composition of 17.65 to 22.18% by weight Cu and 47.87 to 49.68% by weight % S as well as significant contents of 15.58 to 18.24% by weight nickel (Ni), 6.79 to 7.45% by weight cobalt (Co), 4.17 to 6.00% by weight. -% iron (Fe) and 0.88 to 1.54% by weight selenium (Se), which replace part of the copper or sulfur . The empirical mixed formula was given as (Cu, Ni, Co, Fe) (S, Se) 2 .
In 1921 E. Thomson examined the samples again under the ore microscope and found that they were a mixture of two minerals, one of which was white, like a polydymite , the other was dark gray and resembled a mixture. The mineral was therefore discredited in the meantime due to ambiguous data (see also JE Hibsch 1928 and ES Simpson 1932) and was regarded as a variety of Bravoite containing copper and cobalt . A new analysis carried out by Max Hutchinson Hey in 1962 on 9 mg of the type material, on the other hand, resulted in a composition similar to the initial analysis of 24.0% by weight Cu and 54.0% by weight S and 11.8% by weight Ni, 4.0 wt% Co, 5.3 wt% Fe and 0.06 wt% Se.
Crystal structure
Schoeller and Powell concluded on the basis of the observed crystal forms octahedron and cuboctahedron as well as from the measured surface angles, which came very close to the calculated angles of ideal cubic bodies, that Villamanínit must have cubic symmetry. Due to the rough surfaces, the measurements on the goniometer were only imprecise.
Paul Ramdohr was able to show in 1937 that a large part of the material had weathered to form a mixture of chalcopyrite and linnite . According to his analysis, homogeneous material showed in the ore microscopic examination a powder diagram analogous to pyrite , which led to a 0 = 5.65 and 5.59 Å in different zones and addressed these zones as Villamanínite.
It was not until 1996 that Celia Marcos Pascual, A. Paniagua, DB Moreiras, Santiago García-Granda and MR Díaz were able to prove that Villamanínite does not crystallize in a cubic, but in a monoclinic symmetry like the other minerals of the pyrite group. To do this, they selected two Villamaninite crystals from two polished sections of the type material and examined them very carefully. According to the results of this analysis, villamaninite crystallizes in the space group P 2 1 (space group no. 4) with the lattice parameters a = 5.704–5.709 Å; b = 5.703-5.707 Å; c = 5.704-5.708 Å and β = 89.99-90.01 ° as well as 4 formula units per unit cell .
properties
When analyzing the type material, WR Schoeller and AR Powell found that Villamanínit in powder form is soluble in nitric acid , resulting in a greenish-blue, acidic solution and a sulfur ball. Adding ammonia turns the solution deep blue (evidence of copper in the compound). There is also a brown precipitate of iron. By heating in the closed tube, plenty of sulfur and less pronounced selenium is expelled, which is deposited as a sublimate .
With a Mohs hardness of 4.5, Villamanínite is one of the medium-hard minerals that, like the reference minerals fluorite (hardness 4) and apatite (hardness 5), can be scratched with a pocket knife . A multiple measurement carried out of the Vickers - microhardness (VHN) with a test load of 20 g gave a value 535 to 710 kg / mm at globular aggregates 2 and idiomorphic crystals has a value from 440 to 520 kg / mm 2 .
Education and Locations
Villamanínite is mainly formed in dolomite rock , where, in addition to the eponymous mineral dolomite , it can also occur in association with chalcopyrite , pyrite and quartz .
As a rare mineral formation, Villamanínite could only be detected at a few sites, with a little more than 10 sites being documented (as of 2020). Apart from its type locality Mina La Divina Providencia near Villamanín and the nearby Mina La Profunda, the mineral has so far only been found in the Mina Atrevida in Spain, although this location has not yet been confirmed.
In Germany Villamanínit could, among other things in a diorite - Quarry at Steinerleinbach in the Lower Bavarian village of Röhrnbach , the former oberpfälzer Bergbaurevier Wölsendorf in which Graf Jost-Christian-mine in Wolfsberg and in Dietersdorf (municipality Südharz) in Saxony-Anhalt as well as in Lauta ( Marienberg) in the Saxon Erzgebirgskreis.
Other previously known localities are the gold - deposit Shuangwang in circles Taibai in the western Chinese province of Shaanxi , the Cu-Pb-Zn mine Kosaka in the same community Kosaka (Akita) on the Japanese island of Honshu, the Kupferschiefer -Bergwerk in Lubin ( Lower Silesia) and the coal mines with hydrothermal mineralization near Karniowice ( Trzebinia municipality ) in Poland as well as Halibut Bay in the Prince of Wales-Hyder Census Area in the US state of Alaska.
Villamanínite could also be detected in rock samples from the East Pacific Ridge , more precisely at the EPR 21 ° N vent on the Juan de Fuca Ridge .
See also
literature
- WR Schoeller, AR Powell: Villamaninite, a new mineral . In: Nature . tape 104 , 1919, pp. 326 (English, rruff.info [PDF; 1.4 MB ; accessed on July 7, 2020]).
- WR Schoeller, AR Powell: Villamaninite, a new mineral . In: Mineralogical Magazine . tape 19 , 1920, p. 14–18 (English, rruff.info [PDF; 236 kB ; accessed on July 7, 2020]).
- Max Hutchinson Hey : A new analysis of villamaninite . In: Mineralogical Magazine . tape 33 , 1962, pp. 169–170 ( rruff.info [PDF; 112 kB ; accessed on July 7, 2020]).
- Hubert E. King, Charles T. Prewitt: Structure and symmetry of CuS 2 (pyrite structure) . In: American Mineralogist . tape 64 , 1979, pp. 1265–1271 (English, rruff.info [PDF; 675 kB ; accessed on July 7, 2020]).
- Peter Bayliss: Crystal chemistry and crystallography of some minerals within the pyrite group . In: American Mineralogist . tape 74 , 1989, pp. 1168–1176 (English, rruff.info [PDF; 1,2 MB ; accessed on July 13, 2020]).
- Celia Marcos Pascual, A. Paniagua, DB Moreiras, Santiago García-Granda, MR Díaz: Villamaninite, a case of noncubic pyrite-type structure . In: Acta Crystallographica Section B . tape 52 , no. 6 , December 1996, pp. 899–904 , doi : 10.1107 / S0108768196002996 (English, PDF available online for download from researchgate.net [accessed July 7, 2020]).
Web links
- Villamanínit. In: Mineralienatlas Lexikon. Stefan Schorn u. a., accessed on July 7, 2020 .
- Villamanínite. In: mindat.org. Hudson Institute of Mineralogy, accessed July 7, 2020 .
- David Barthelmy: Villamaninite Mineral Data. In: webmineral.com. Retrieved July 7, 2020 .
- American-Mineralogist-Crystal-Structure-Database - Villamanínite. In: rruff.geo.arizona.edu. Retrieved July 7, 2020 .
Individual evidence
- ↑ a b Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: July 2020. (PDF; 2.44 MB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, July 2020, accessed July 7, 2020 .
- ^ 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. 103 (English).
- ↑ 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. 320 .
- ↑ a b c Celia Marcos Pascual, A. Paniagua, DB Moreiras, Santiago García-Granda, MR Díaz: Villamaninite, a case of noncubic pyrite-type structure . In: Acta Crystallographica Section B . tape 52 , no. 6 , December 1996, pp. 899–904 , doi : 10.1107 / S0108768196002996 (English, PDF available online for download from researchgate.net [accessed July 7, 2020]).
- ↑ a b c d e f Villamanínite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 (English, handbookofmineralogy.org [PDF; 65 kB ; accessed on July 7, 2020]).
- ^ Friedrich Klockmann : Klockmanns textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 459 (first edition: 1891).
- ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties. Status 03/2018 . 7th, completely revised and supplemented edition. Weise, Munich 2018, ISBN 978-3-921656-83-9 .
- ↑ Ernest H. Nickel , Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF; 1.82 MB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed July 7, 2020 .
- ^ A b c WR Schoeller, AR Powell: Villamaninite, a new mineral . In: Mineralogical Magazine . tape 19 , 1920, p. 14–18 (English, rruff.info [PDF; 236 kB ; accessed on July 7, 2020]).
- ^ Helmut Schrätze , Karl-Ludwig Weiner : Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp. 252 .
- ^ A b Max Hutchinson Hey : A new analysis of villamaninite . In: Mineralogical Magazine . tape 33 , 1962, pp. 169–170 ( rruff.info [PDF; 112 kB ; accessed on July 7, 2020]).
- ↑ a b List of locations for Villamanínite from the Mineralienatlas and Mindat , accessed on July 7, 2020.
- ^ Villamaninite from EPR 21 ° N, Juan de Fuca Ridge complex, East Pacific Rise, Pacific Ocean. In: mindat.org. Hudson Institute of Mineralogy, accessed July 7, 2020 .