Anglesite
Anglesit, also under the mining designations Bleivitriol or Vitriolbleierz or chemically as lead ( II) sulfate is known, is a rarely occurring mineral from the mineral class " Sulfate ( and relatives ) ." It crystallizes in the orthorhombic crystal system with the chemical composition Pb [ SO4 ] and developed mostly well-educated, area- rich crystals with tabular, prismatic or dipyramidalem habitus, their surfaces are often streaked along the c axis and have a diamond to grease-like luster. However Anglesit can also bulbous, stalaktitischen, granular or massive mineral aggregates or coarse crust wrapped around a core of galena occur.
Also pseudomorphs of anglesite after galena or conversions to and from Cerussite are known.
Special Features
Reiner Angelesit is colorless and transparent. But it can also yellowish-white, be colored gray or greenish and his Translucent decreases correspondingly by foreign admixtures. With a Mohs hardness of 2.5 to 3 Anglesit still belongs to the soft mineral and can be scratched, for example, with a copper coin.
Its density is depending on the purity from 6.3 to 6.4 g / cc (calculated: 6.36 g / cc), which is about 50 % higher than the density of very similar appearance to barite barite. In addition, Anglesit dissolves in concentrated sulfuric acid and potassium hydroxide solution in barite and celestite in contrast to.
Under the action of UV light, the mineral is sometimes a weak, yellowish fluorescence.
Etymology and history
Already in 1779 described Antoine Grimoald Monet, a French mining Inspector General in his " Nouveau Système de mineralogy " a newly discovered mineral that had been found close to Parys in Amlwch on the Welsh island of Anglesey, as vitriol de plomb (English: sulphate of lead, translated: " sulphate of lead ").
His final name of the mineral anglesite was not until 1832, however, by François Sulpice Beudant ( 1787-1850 ), a French mineralogist and physicist, who named the mineral after its type locality Anglesey.
Classification
In the now outdated but still in use 8th edition of the mineral classification by Strunz the Anglesit the mineral class of " sulfates, selenates, tellurates, chromates, molybdates and tungstates " belonged and there to the Department of " Anhydrous sulfates without foreign anions ", where he with barite, celestite and Hashemit the " Barytgruppe " was formed.
The 9th edition used since 2001 and valid by the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the Anglesit also in the class of " sulfates ( selenates, tellurates, chromates, molybdates and tungstates ) " and then in the Department of " Sulfate ( selenates, etc. ) without additional anions, without H2O" one. This division, however, is further divided according to the size of the cations involved, so that the mineral is "With only large cations " to find according to its composition in the subdivision where it together with barite, celestite and Olsacherit the still existing " Barytgruppe " with the system number. 7.AD.35 forms.
The classification of minerals according to Dana assigns the Anglesit in the class of " sulfates, chromates, molybdates, selenates, tellurates, Selenite, Tellurite and sulphites " and there in the department of " sulfates " one. Here he is with barite and celestite in the " Barytgruppe " with the system no. Find 3.28.01 within the sub-division of " water clear acids and sulfates (A2 ) XO4 ".
Education and Locations
Anglesit formed by oxidation of galena ( galena ) and can thus be found mostly in paragenesis with this and other lead minerals such as cerussite, Lanarkit, Leadhillit, Massicotit, Mimetite, pyromorphite, Wulfenite, but also lead-copper or copper minerals such as Brochantite, Caledonit, Linarit, malachite and gypsum and native sulfur.
Could Worldwide Anglesit so far (as of 2011) are detected at around 2000 localities. Notable localities due to their particularly beautiful trained and / or large crystals are mainly the Prince colliery at Lam in the Upper Palatinate (Bavaria), where the emerald green (Bayer Forest Emerald ) and fire-red, clearly defined, anglesite crystals were revealed. Up to 10 cm long, yellowish Anglesitkristalle could be found in the Moroccan Touissit in Oujda - Angad Prefecture. From the " Bunker Hill Mine" at Kellogg Shoshone County (Idaho, USA) is known Anglesitfunde of up to 7.5 cm in length and in the " Tsumeb Mine " in Namibia Crystals are found to about 4 cm in size.
At German localities are adjacent to the Prince colliery in Bavaria, among others, which are also located in Bavaria communities still Schmölz, Roehrnbach, Forest aces and Schwandorf; many areas of the Black Forest in Baden- Württemberg, Odenwald, Spessart and Taunus in Hesse; several points in the Fund resin in Lower Saxony and Saxony -Anhalt; the Aachen district, the Bergische Land, the Eifel, the Sauer - winning country and in North Rhine -Westphalia; Hunsrück and Westerwald Lahn, in Rhineland -Palatinate; Nalbach in Saarland; the Ore Mountains in Saxony known and Gera, Greiz and Wurzbach in Thuringia.
In Austria, Anglesit found in many parts of Carinthia, on the Black Mountain in the Türnitzer Alps ( Lower Austria), in several regions of Salzburg and Styria as well as in North Tyrol.
In Switzerland, the mineral so far could be found in the cantons of Bern, Graubünden, Ticino, Uri, Valais and Vaud.
Other localities are Argentina, Australia, Belgium, Bolivia, Brazil, Bulgaria, Chile, China, Eritrea, France, Gabon, Greece, India, Indonesia, Iran, Ireland, Italy, Japan, Canada, the Channel Islands of Jersey and Little Sark, Kazakhstan, the Democratic Republic of Congo, Kosovo, Cuba, Luxembourg, Madagascar, Morocco, Macedonia, Mexico, Mongolia, Namibia, New Caledonia, New Zealand, Norway, Poland, Portugal, Romania, Russia, Zambia, Sweden, Zimbabwe, Slovakia, Slovenia, Spain, South Africa, Tunisia, Turkey, Ukraine, Uzbekistan, the United Kingdom ( UK) and the United States of America (USA).
Crystal structure
Anglesit crystallizes isotypic with barite in the orthorhombic crystal system, space group ( Raumgruppen-Nr. 62) with the lattice parameters a = 8.48 Å; b = 5.40 Å and c = 6.96 Å and four formula units per unit cell.
The slightly distorted [ SO4 ] 2 - tetrahedra with sulfur at the center are connected heteropolar with the 12-fold coordinated by oxygen Blei2 ions. The crystal structure can be simplified as a deformed sodium chloride structure described, in which the sodium ions are replaced with chlorine ions and lead ions by [ SO4 ] tetrahedra.
Use
Despite his lead content of up to 68.3 % is Anglesit than lead - ore only of local importance for industrial smelting.
As a gemstone Anglesit has because of its poor physical properties (hardness, cleavage ) of no importance. Occasionally he is also potentially of hobby grinders with different smooth or faceted cuts in the form and then among interested collectors as barter and sale object a certain sentimental value.