Wulfenite
- Gelbbleierz
- Melinose
- Molybdenum - lead ore
- Molybdenum Bleispat
- Molybdenum yellow
Wulfenite, also known as molybdenum - lead ore or - Bleispat, Gelbbleierz or molybdenum yellow, is a commonly occurring mineral from the mineral class of " sulfates ( and Related, see classification) ". It crystallizes in the tetragonal crystal system with the idealized chemical composition Pb [ MoO4 ], and is therefore chemically seen a lead molybdate.
Wulfenite is transparent to translucent and usually develops thin, tabular or bipyramidal crystals, but can also occur in coarse -grained to aggregates. Visible crystal faces have a fat-like up diamond-like luster. The color of Wulfenite varies mainly between yellow, orange and red.
Special Features
In its pure form is Wulfenite is colorless and transparent or by multiple light scattering due to lattice defects or polycrystalline training also white. However, it can take a wide range of colors ranging from light yellow to orange to red by foreign admixtures of calcium, vanadium, arsenic, chromium and / or titanium. Even light to dark blue, greenish, reddish brown to black crystals are known.
Wulfenite is among others in sulfuric acid and ethanol slightly soluble and blue coloring. Before blowtorch Wulfenite is easy to melt and can be reduced with carbon to lead.
Etymology and history
Wulfenite was first found in 1785 in Bad Bleiberg in the Austrian province of Carinthia and named after its describer Franz Xaver Freiherr von Wulfen ( 1728-1805 ), an Austrian naturalist.
Classification
In the now outdated but still in use 8th edition of the mineral classification by Strunz the Wulfenite the mineral class of " sulfates, chromates, molybdates, tungstates " and then to the Department of " molybdates and tungstates " belonged, together with Paraniit - (Y), where he, Powellit, scheelite and Stolzit the " Scheelite group " with the system no. VI/G.01 formed.
The 9th edition used since 2001 and valid by the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the Wulfenite in the extended class of " sulfates (including selenates, tellurates, chromates, molybdates and tungstates ) " and then in the Department the " molybdates and tungstates " one. However, this is further subdivided according to the possible presence of additional anions and crystal water, so that the mineral is found according to its composition in the subsection "Without additional anions or H2O", where it together with fergusonite - (Ce), fergusonite - (Nd), fergusonite - (Y), Formanit - (Y), Powellit, scheelite and Stolzit the unnamed group 7.GA.05 forms.
The mostly commonly used in English-speaking classification of minerals according to Dana assigns the Wulfenite contrast to the category of " phosphates, arsenates and vanadates " and there in the department of " molybdates and tungstates " one. Here he is with Stolzit in the eponymous " Wulfenite series" with the system no. 48.01.03 found within the subdivision " anhydrous molybdates and tungstates with A XO4 ".
Education and Locations
As a typical secondary mineral is Wulfenite forms by oxidation of galena. Accompanying minerals are anglesite, cerussite, Vanadinit and others. Often pseudomorphs of Wulfenite occur after galena, cerussite and anglesite.
As a frequent mineral formation Wulfenite is found in many localities, where so far (as of 2013) are approximately 1,600 localities known as. Apart from its type locality Bad Bleiberg the mineral in Austria was among others still at many other locations in the Gail Valley Alps, Carnic Alps, Gurktaler Alps, Karawanken and the Hohe Tauern Carinthia to Salzburg; at Annaberg and other places in Lower Austria; at Kaltenegg and Arzberg am Semmering found in the Fischbacher Alps and the Obert Albach Valley in Styria and in different places in Tyrol.
In Germany they found Wulfenite in many places in the Black Forest in Baden- Württemberg, in some places in Lower Bavaria, Upper Bavaria and the Upper Palatinate, to some discovery locations in the Hessian Odenwald, in the vicinity of Duren and Mechernich in the Eifel and in Velbert and Flandersbach (Region Flandersbach ) in North Rhine -Westphalia; at Dannenfels, Imsbach and Nothweiler in Rhineland -Palatinate; at Neudorf and Strassberg in Saxony -Anhalt; in many places in the Saxon Erzgebirge and in Neumühle / Elster, Gräfenroda and Weitisberga in Thuringia.
Other localities lie among others in Algeria, Argentina, Australia, Belgium, Bolivia, Chile, China, Germany, France, Gabon, Italy, Canada, Democratic Republic of the Congo, Morocco, Namibia, Norway, Czech Republic, United Kingdom ( UK) and the United States of America (USA).
Crystal structure
Wulfenite crystallizes in the tetragonal crystal system, space group I41 / a ( Raumgruppen-Nr. 88) with the lattice parameters a = 5.43 Å and c = 12.11 Å and four formula units per unit cell.
Use
For local accumulation Wulfenite is mined as ore because of its high lead and molybdenum content. Even if Wulfenite sometimes forming beautiful and clear crystals, it is uninteresting as a gemstone for the commercial jewelry industry due to its low hardness. Faceted by skilled hobby grinders he can become a coveted exchange or purchase item for collectors yet.
Applies Wulfenite crystal as an active in acousto-optical modulators, which are generated by acoustic waves density fluctuations in the crystal. These density fluctuations then act as an optical grating and direct parts of the incident light beams depending on acoustic frequency.