Susannite
- Suzannit
Susannite is a rarely occurring mineral from the mineral class of " carbonates and nitrates ." It crystallizes in the trigonal crystal system with the composition Pb4 [( OH) 2 | ( CO3) 2 | SO4 ], and is therefore chemically seen a lead double salt.
Susannite found mostly in the form of millimeter-sized, isometric and rhombohedral crystals. In its pure form it is colorless and transparent. He can, however, also appear white and accept by foreign admixtures a pale green, pale yellow or brown color by multiple refraction due to lattice defects or multicrystalline training. However, the line color is always white.
Special Features
Under UV light, show some Susannite a strong lemon-yellow fluorescence.
On charcoal before the blowpipe swells Susannite heated slightly, turns yellow, and reduced to lead. In nitric acid dissolves the mineral roaring on with the release of carbon dioxide. The residual, poorly soluble lead sulphate forms a white precipitate.
Etymology and history
Was first discovered in the Susannite " Susanna Mine" (also called " Glennery Scar " - " Susanna " - " Portobello ", " Humby " - or "Lead" - transition ) at Leadhills in Scotland, United Kingdom.
A first mention of the mineral was carried out in 1820 by Henry James Brooke, who analyzed the Sulphato - tricarbonat of lead from Leadhills and described his form as rhombohedral ( trigonal ). Wilhelm Ritter von Haidinger, however, held the form of two - and eingliedrig (monoclinic and triclinic ) and gave the mineral in 1845 based on its type locality the name Susannite (or Suzannit ). Later studies by Brooke and Miller showed, however, that in Leadhills two lead double salts of the same composition to occur, and the Leadhillit monoclinic and the trigonal Susannite ( rhombohedral ) is.
Classification
In the now outdated but still in use 8th edition of the mineral classification by Strunz the Susannite still belonged to the mineral class of " sulfates, selenates, tellurates, chromates, molybdates, tungstates " and then to the Department of " water clear sulfates with foreign anions ," where he together with Grandreefit, Lanarkit, Leadhillit, Macphersonit, Olsacherit and Pseudograndreefit the independent group VI/B.13 formed.
The 9th edition used since 2001 and valid by the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the Susannite other hand, in the class of " carbonates and nitrates " and there in the department of " Carbonates with additional anions, without H2O" one. This department is also further divided by type of other anions, so that the mineral is found according to its composition in the subsection "With Cl, SO4, PO4 " where there is only together with Leadhillit and Macphersonit the " Leadhillitgruppe " with the System no. 5.BF.40 forms.
The mostly commonly used in English-speaking classification of minerals according to Dana assigns the Susannite in the class of " carbonates, nitrates and borates " and there in the department of " Composite carbonates " one. Here he can be found as the only member of the unnamed group 17:01:03 within the subdivision " Composite carbonates with different formulas ."
Modifications and varieties
The connection Pb4 [( OH) 2 | ( CO3) 2 | SO4 ] is trimorph and comes in addition to the trigonal crystallized Susannite in nature nor as monoclinic Leadhillit crystallizing and crystallizing as orthorhombic Macphersonit ago.
Education and Locations
Susannite formed as a secondary mineral in the oxidation zone of lead-containing reservoirs at a temperature of about 80 ° C. Accompanying minerals are other lead minerals such as Caledonit, Cerussite, Lanarkit, Leadhillit and Macphersonit.
A rare mineral formation Susannite has so far (as of 2011) are detected only at a few localities. About 90 localities are considered to be known. Apart from its type locality " Susanna Mine" the mineral still occurred in several mines in Caldbeck Fells and the quarry at Whitwell in the English county of Cumbria in the United Kingdom; in several mines at Leadhills and Wanlockhead in Scotland and in many mines in the Welsh region in Ceredigion.
In Germany Susannite Among other findings in the Black Forest; on the slag heap near Richelsdorf and in the " pit Association " in Eisenbach in Hesse; at several places in Lower Saxony Harz; in different pits or on slag heaps in North Rhine -Westphalia; in several places in Rhineland -Palatinate and in the pit "Holy Trinity " at Zschopau in the Saxon Erzgebirge.
The only known locality in Austria is Arzberg am Semmering in Hasental near the steiermarker Spital am Semmering.
Other localities lie including France, Greece, Ireland, Italy, Namibia, Romania, Russia, Czech Republic and the United States of America (USA).
Crystal structure
Susannite crystallizes in the space group P3 ( Raumgruppen-Nr. 143) with the lattice parameters a = 9.07 Å and c = 11.57 Å and 3 formula units per unit cell.