Wulfenite
| Wulfenite | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula | Pb [MoO 4 ] |
|
Mineral class (and possibly department) |
Sulfates (including selenates, tellurates, chromates, molybdates, and tungstates) |
|
System no. to Strunz and to Dana |
7.GA.05 ( 8th edition : VI / G.01) 48.01.03.01 |
| Crystallographic Data | |
| Crystal system | tetragonal |
| Crystal class ; symbol | tetragonal-dipyramidal; 4 / m |
| Space group | I 4 1 / a (No. 88) |
| Lattice parameters | a = 5.43 Å ; c = 12.11 Å |
| Formula units | Z = 4 |
| Frequent crystal faces | tabular after [001], pyramidal {011} |
| Twinning | Contact twins after {001} |
| Physical Properties | |
| Mohs hardness | 2.5 to 3 |
| Density (g / cm 3 ) | measured: 6.5 to 7.5; calculated: 6.88 to 7.48 |
| Cleavage | clearly after {011}; indistinct after {001} and {013} |
| Break ; Tenacity | slightly scalloped to uneven; brittle |
| colour | yellow, orange, red; rarely colorless, light to dark blue, greenish, reddish brown to black |
| Line color | White |
| transparency | transparent to opaque |
| shine | Greasy gloss to diamond gloss |
| Crystal optics | |
| Refractive indices |
n ω = 2.405 n ε = 2.283 |
| Birefringence | δ = 0.122 |
| Optical character | uniaxial negative |
| Axis angle | 2V = 8 ° (measured) |
Wulfenit , also known as molybdenum-lead ore and -Bleispat , yellow lead ore or molybdenum Yellow known is a common mineral from the mineral class of " Sulfate (and relatives, see Classification )." It crystallizes in the tetragonal crystal system with the idealized chemical composition Pb [MoO 4 ], so it is chemically a lead - molybdate .
Wulfenite is transparent to translucent and usually develops thin, tabular or bipyramidal crystals , but can also occur in granular to coarse aggregates . Visible crystal surfaces have a fat-like to diamond-like sheen . The color of wulfenite mainly varies between yellow, orange and red.
Etymology and history
Wulfenite was first found in 1785 in Bad Bleiberg in the Austrian state of Carinthia and named after its first describer Franz Xaver Freiherr von Wulfen (1728–1805), an Austrian naturalist. On the occasion of the 175th anniversary of its naming, Wulfenit was voted "Mineral of the Year" in Austria in 2020.
classification
In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the wulfenite belonged to the mineral class of "sulfates, chromates, molybdates, wolframates" and there to the department of "molybdates and wolframates", where together with paraniite (Y) , Powellit , Scheelit and Stolzit the "Scheelit Group" with the system no. VI / G.01 .
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), assigns wulfenite to the extended class of "sulfates (including selenates, tellurates, chromates, molybdates and wolframates)" and there into the department the "Molybdates and Wolframates". However, this is further subdivided according to the possible presence of additional anions and water of crystallization , so that the mineral can be found according to its composition in the subsection "Without additional anions or H 2 O", where it can be found together with fergusonite (Ce) , fergusonite ( Nd) , fergusonite (Y) , formanite (Y) , powellite, scheelite and stolzite form the unnamed group 7.GA.05 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns wulfenite, however, to the class of "phosphates, arsenates and vanadates" and there to the department of "molybdates and tungstates". Here he is together with Stolzit in the "Wulfenit series" named after him with the system no. 48.01.03 to be found in the sub-section " Anhydrous molybdates and tungstates with A XO4 ".
Crystal structure
Wulfenite crystallizes in the tetragonal crystal system in space group I 4 1 / a (space group no. 88) with the lattice parameters a = 5.43 Å and c = 12.11 Å as well as four formula units per unit cell .
properties
In its pure form, wulfenite is colorless and transparent or, due to multiple light refraction due to lattice construction defects or polycrystalline formation, also white. However, through the addition of calcium , vanadium , arsenic , chromium and / or titanium , it can take on a wide range of colors, ranging from light yellow to orange to red. Light to dark blue, greenish, reddish brown to black crystals are also known.
Wulfenite is decomposed by acids and forms a blue solution with sulfuric acid and ethanol . In front of the soldering tube, wulfenite crackles and melts easily. Together with coal it can be reduced to lead .
Modifications and varieties
The only known variety so far is the tungsten-containing chillagite . This was first discovered in the Christmas Gift opencast copper, lead and silver mine near Chillagoe in the Australian state of Queensland and first described as a new type of mineral in 1912 by Albert Thomas Ullman . However, recent investigations by Christine M. Jury, Peter Leverett, Peter A. Williams, Ian R. Plimer and David E. Hibbs were able to prove that Chillagit is a mixed crystal of the series wulfenite– stolzite (Pb [WO 4 ]) with the corresponding mixed formula Pb Is [(Mo, W) O 4 ].
Education and Locations
As a typical secondary mineral , wulfenite is formed by oxidation from galena . Accompanying minerals are angelsite , cerussite , vanadinite and others. Often, pseudomorphoses from wulfenite to galena, cerussite and anglesite occur.
As a frequent mineral formation, wulfenite can be found in many localities, whereby so far (as of 2013) around 1600 localities are known. In addition to its type locality Bad Bleiberg, the mineral was found in Austria in many other places in the Gailtal Alps , Carnic Alps , Gurktal Alps , Karawanken and the Hohe Tauern from Carinthia to Salzburg, near Annaberg and other places in Lower Austria, near Kaltenegg and Arzberg found at Semmering in the Fischbacher Alps and the Obertalbach valley in Styria as well as in various places in Tyrol .
In Germany, wulfenite was found in many places in the Black Forest in Baden-Württemberg, in some places in Lower Bavaria , Upper Bavaria and the Upper Palatinate , at some sites in the Hessian Odenwald , in the vicinity of Düren and Mechernich in the Eifel and near Velbert and Flandersbach (region Flandersbach) in North Rhine-Westphalia; near Dannenfels , Imsbach and Nothweiler in Rhineland-Palatinate; near Neudorf and Straßberg in Saxony-Anhalt; in many places in the Saxon Ore Mountains as well as at Neumühle / Elster , Gräfenroda and Weitisberga in Thuringia.
Other locations include Algeria , Argentina , Australia , Belgium , Bolivia , Chile , China , Germany , France , Gabon , Italy , Canada , the Democratic Republic of the Congo , Morocco , Namibia , Norway , the Czech Republic , the United Kingdom (Great Britain) and the United States United States of America (USA).
use
If it accumulates locally, wulfenite is mined as ore due to its high lead and molybdenum content. Even if wulfenite sometimes forms beautiful and clear crystals, it is of no interest as a gemstone for the commercial jewelry industry due to its low hardness. Faceted by experienced hobby cutters, it can nonetheless become a coveted object of exchange or purchase for collectors.
Wulfenite is used as an active crystal in acousto-optical modulators , where acoustic waves generate density fluctuations in the crystal. These fluctuations in density then act like an optical grating and deflect parts of the incident light rays depending on the acoustic frequency .
See also
literature
- W. Haidinger : Handbook of determining mineralogy, containing the terminology, systematics, nomenclature and characteristics of the natural history of the mineral kingdom . Braumüller & Seidel, Vienna 1845, p. 499–506 ( rruff.info [PDF; 512 kB ; accessed on September 24, 2018]).
- Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 620–621 (first edition: 1891).
- C. Lugli, Luca Medici, D. Saccardo: Natural wulfenite: structural refinement by single-crystal X-ray diffraction . In: New yearbook for mineralogy, monthly books . tape 6 , no. 6 , 1999, p. 281-288 (English).
- Petr Korbel, Milan Novák: Mineral Encyclopedia (= Villager Nature ). Edition Dörfler im Nebel-Verlag, Eggolsheim 2002, ISBN 978-3-89555-076-8 , p. 153 .
Web links
- Mineralienatlas: Wulfenite and Mineralienatlas: Mineralienportrait / Wulfenit (Wiki)
- Database-of-Raman-spectroscopy - Wulfenite
- American-Mineralogist-Crystal-Structure-Database - Wulfenite
- Carinthia mineral stand. Wulfenite. In: www.indra-g.at. Indra Günther, February 2012, accessed on September 24, 2018 (mineral short description and literature list).
Individual evidence
- ^ Archive of Pharmacy , annual edition 1841, p. 204 full text in the Google book search
- ↑ Webmineral - Wulfenite
- ^ A b c Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 419 .
- ↑ a b c Wulfenite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 67.5 kB )
- ↑ a b c d Mindat - Wulfenite
- ↑ Mineral of the year in Austria. Retrieved February 2, 2020 (German).
- ^ Friedrich Klockmann : Klockmanns textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 620 (first edition: 1891).
- ^ AT Ullmann: A new mineral . In: Journal and Proceedings of the Royal Society of New South Wales . tape 46 , 1912, pp. 186 ( available online at biodiversitylibrary.org [accessed October 31, 2018]).
- ↑ Christine M. Jury, Peter Leverett, Peter A. Williams, Ian R. Plimer, David E. Hibbs: Mineralogical note: the status of 'chillagite' . In: Australian journal of mineralogy . tape 7 , no. 1 , 2001, p. 39 (English, abstract from Western Sydney University online [accessed October 31, 2018]).
- ↑ MinDat - Localities for Wulfenite (English)
- ↑ Find location list for wulfenite in the Mineralienatlas and Mindat
- ^ Walter Schumann: Precious stones and gemstones . 13th edition. BLV, Munich 2002, ISBN 3-405-16332-3 .
- ↑ realgems.org - wulfenite (with picture examples of polished wulfenite)