Sengierite
| Sengierite | |
|---|---|
 |
|
| General and classification | |
| chemical formula |
|
|
Mineral class (and possibly department) |
Oxides and hydroxides (formerly phosphates, arsenates and vanadates) |
|
System no. to Strunz and to Dana |
4.HB.10 ( 8th edition : VII / E.11) 42.06.10.01 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Room group (no.) | P 2 1 / a (No. 14) |
| Lattice parameters |
a = 10.60 Å ; b = 8.09 Å; c = 10.09 Å β = 103.4 ° |
| Formula units | Z = 2 |
| Frequent crystal faces | {001}, {110}, {100}, {201}, {111} |
| Physical Properties | |
| Mohs hardness | 2.5 |
| Density (g / cm 3 ) | measured: 4.05; calculated: 4.10 |
| Cleavage | completely after {001} |
| Break ; Tenacity | brittle |
| colour | yellowish green to greenish yellow |
| Line color | light green |
| transparency | transparent |
| shine | Glass gloss to diamond gloss |
| radioactivity | very strong |
| Crystal optics | |
| Refractive indices |
n α = 1.760 to 1.770 n β = 1.920 to 1.940 n γ = 1.940 to 1.970 |
| Birefringence | δ = 0.180 to 0.200 |
| Optical character | biaxial negative |
| Axis angle | 2V = measured: 37 ° to 39 °; calculated: 36 ° |
| Pleochroism | visible: X = bluish green to colorless, Y = olive green to greenish yellow, Z = yellowish green to colorless |
| Other properties | |
| Chemical behavior | soluble in acids |
Sengierite is a very rare mineral from the mineral class of "oxides and hydroxides" (formerly phosphates, arsenates and vanadates ). It crystallizes in the monoclinic crystal system with the chemical composition Cu 2 (OH) 2 [UO 2 | VO 4 ] 2 · 6H 2 O and is therefore chemically speaking, a basic, water-containing copper - uranyl - vanadate , that a particular group of the oxides or Hydroxide, the so-called Polyvanadaten (V [5,6] -Vanadate) belongs. Structurally, Sengierite is one of the uranyl group vanadates (sorovanadates).
The mineral develops tabular crystals with a six-sided outline up to about two millimeters in diameter, which are usually connected to scaly mineral aggregates and crusty coatings. The transparent crystals are yellowish-green to olive-green in color with a light green line color and have a glass -like to diamond-like sheen on the surfaces .
Etymology and history
Was first discovered in Sengierit copper - cobalt - uranium - open pit Luiswishi about 20 kilometers north of Lubumbashi in the Katanga province and described the DRC in 1949 by F. John F. Vaes, Paul Kerr, the mineral after the former director of the Union Mine named by Katanga Edgar Sengier (1879–1963).
CO Hutton of Stanford University in California examined mineral samples from the Cole Mine, Bisbee, Arizona (USA) in 1957. The material came from the former director of the mine, William P. Crawford, which he found in 1935.
The type mineral is stored at Harvard University in Cambridge , Massachusetts in the USA (Catalog No. 103963).
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the sengierite still belonged to the mineral class of " phosphates , arsenates and vanadates " and there to the department of "uranyl phosphates / arsenates and uranyl vanadates ", where together with carnotite , curienite , Francevillit , Margaritasit , Metatyuyamunit , Metavanuralit , Strelkinit , Tyuyamunit and Vanuralit the group of the "Uranyl group vanadates with [UO 2 ] 2+ - [V 2 O 8 ] 6− " with the system no. VII / E.11 formed.
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 sengierite to the class of "oxides and hydroxides" and there in the department of "V [5,6] vanadates" . This is further subdivided according to the crystal structure , so that the mineral can be found according to its structure in the sub-section "Uranyl group vanadates (Sorovanadates)", where it is the only member of the unnamed group 4.HB.10 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , classifies sengierite as the outdated Strunz system in the class of "phosphates, arsenates and vanadates", but there in the department of "water-containing phosphates etc., with hydroxyl or halogen ". Here he is to be found as the only member in the unnamed group 42.06.10 within the sub-section “Water-containing phosphates etc.”, with hydroxyl or halogen with (AB) 2 (XO 4 ) Z q × x (H 2 O).
Crystal structure
Sengierite crystallizes monoclinically in the space group P 2 1 / a (space group no. 14) with the lattice parameters a = 10.60 Å ; b = 8.09 Å, c = 10.09 Å and β = 103.4 ° as well as two formula units per unit cell . Sengierite consists of layers of edge-sharing pentagonal-bipyramidal uranyl and square-pyramidal vanadate polyhedra. The layers are linked both by hydrogen bonds and by the coordination of the oxygen atoms of the vanadate polyhedra by Cu 2+ ions.
properties
Due to its uranium content of up to 47.36%, the mineral is very radioactive . Taking into account the natural series of decay or any decay products present, the specific activity is given as 84.78 k Bq / g (for comparison: natural potassium 0.0312 kBq / g). The quoted value can vary significantly depending on the mineral content and the composition of the levels; selective enrichment or depletion of the radioactive decay products is also possible and changes the activity.
Education and Locations
Sengierite forms secondary in copper-containing uranium deposits through the deposition of hydrothermal solutions that convert the uraninite that is primarily present . It occurs there mainly in paragenesis with chalcosine , chlorargyrite , chrysocolla , various cobalt oxides , covelline , malachite , tyuyamunite , Vandenbrandeit and volborthite .
As a very rare mineral formation, Sengierite could so far (as of 2014) only be found in a few samples from less than 10 sites. In addition to its type locality Luiswishi Mine near Lubumbashi, the mineral was also found in the Democratic Republic of the Congo in the Musonoi Mine near Kolwezi and the Shinkolobwe Mine (Kasolo Mine) in Katanga.
Other previously known sites are the Huemul Min in the Pampa Amarilla in the Argentine department Malargüe , the Clara mine near Oberwolfach in the German state of Baden-Württemberg, Rabejac in the French department of Hérault , Amelal in Morocco , the Eureka mine (municipality of Torre de Cabdella ) in the Spanish province of Lleida , Růžodol (German Rosenthal ) in the Czech region of Bohemia and the Cole mine near Bisbee in the US state of Arizona.
Precautions
Due to the toxicity and the strong radioactivity of the mineral, mineral samples of sengierite should only be kept in dust- and radiation-tight containers, but especially never in living rooms, bedrooms or work rooms. Absorption into the body (incorporation, ingestion ) should also be prevented in any case and, for safety, direct body contact should be avoided and respiratory protection mask and gloves should be worn when handling the mineral .
See also
literature
- JF Vaes, Paul F. Kerr: Sengierite: a preliminary description. In: American Mineralogist. Volume 34, 1949, pp. 109-120 ( rruff.info PDF; 748.1 kB).
- Gabrielle Donnay, JDH Donnay: Contribution to the crystallography of uranium minerals. In: Geological Survey for the United States Atomic Energy Commission. Technical Information Service Oak Ridge, April 1955, pp. 1-42 ( rruff.info PDF; 1.56 MB).
- Sengierite. in: Clifford Frondel : Systematic Mineralogy of Uranium and Thorium. Volume 1064, Geological Survey Bulletin, US Government Printing Office, 1958, pp. 258-260 ( limited preview in Google Book Search).
- Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 656 (first edition: 1891).
Web links
- Mineral Atlas: Sengierite
- Photos of Sengierit on the website of the Association des Géologues Amateurs de Belgique (AGAB)
- Database-of-Raman-spectroscopy - Sengierite.
Individual evidence
- ↑ a b c d e 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. 255 .
- ^ IMA / CNMNC List of Mineral Names; March 2014 (PDF; 1.5 MB).
- ↑ a b c Webmineral - Sengierite.
- ↑ a b c d Sengierite. In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America. 2001 ( handbookofmineralogy.org PDF; 65.3 kB).
- ↑ a b c d Mindat - Sengierite.
- ↑ Mineral Atlas - Sengierite.
- ↑ Mineralienatlas - type locality Luiswishi, Katanga (Shaba), Democratic Republic of the Congo
- ^ JF Vaes, Paul F. Kerr: Sengierite: a preliminary description. In: American Mineralogist. Volume 34, 1949, pp. 109-120 ( rruff.info PDF; 748.1 kB).
- ^ CO Hutton: Sengierite from Bisbee, Arizona. In: American Mineralogist. Volume 42, 1957, pp. 408-411 ( minsocam.org PDF; 263 kB).
- ↑ Find location list for sengierite in the Mineralienatlas .