Zeunerite
| Zeunerite | |
|---|---|
 |
|
| General and classification | |
| other names |
Copper arsenic uranium |
| chemical formula |
|
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.EB.05 ( 8th edition : VII / D.20a) 40.02a.14.01 |
| Crystallographic Data | |
| Crystal system | tetragonal |
| Crystal class ; symbol | ditetragonal-dipyramidal; 4 / m 2 / m 2 / m |
| Space group | P 4 / nnc (No. 126) |
| Lattice parameters | a = 7.18 Å ; c = 20.79 Å |
| Formula units | Z = 2 |
| Frequent crystal faces | {001} |
| Physical Properties | |
| Mohs hardness | 2.5 |
| Density (g / cm 3 ) | measured: 3.47; calculated: [3.57] at 16H 2 O |
| Cleavage | completely after {001}, clearly after {100} |
| colour | yellow green, emerald green |
| Line color | pale green |
| transparency | transparent to translucent |
| shine | Glass gloss |
| radioactivity | very radioactive |
| Crystal optics | |
| Refractive indices |
n ω = 1.610 to 1.613 n ε = 1.582 to 1.585 |
| Birefringence | δ = 0.028 |
| Optical character | uniaxial negative |
| Pleochroism | visible: ω = blue-green; ε = light blue-green |
| Other properties | |
| Chemical behavior | frequent drainage to metazeunerite |
| Special features | highly toxic, no luminescence |
Zeunerite (also copper arsenuranite ) is a rather seldom occurring mineral from the mineral class of “phosphates, arsenates and vanadates” with the chemical composition Cu [UO 2 | AsO 4 ] 2 · 10–12H 2 O and thus, chemically speaking, a water-containing copper - uranyl - arsenate .
Zeunerite crystallizes in the tetragonal crystal system and develops mostly flat, tabular crystals of yellow-green to emerald-green color, the shape of which is dominated by the base surface {001}. The surfaces of the transparent crystals show a glass-like sheen . Zeunerite leaves a pale green line on the marking board .
With a Mohs hardness of 2.5, zeunerite is still one of the soft minerals that can no longer be scratched with a fingernail, but is easier to scratch with a copper coin than the reference mineral calcite (3).
The mineral dehydrates easily to metazeunerite (Cu [UO 2 | AsO 4 ] 2 · 8H 2 O), whereby its transparency is reduced by the loss of water, that is, it becomes cloudy. Finds made of pure Zeunerite with a maximum content of crystal water are rare.
Etymology and history
A first description of the “mica viridis” or “green mica” ( torbernite in this case) comes from Born in 1772. Around 1800, only a few years after the discovery of the element uranium , Martin Heinrich Klaproth was able to find this new element in the uranium glimmer prove.
Zeunerite was not described as an independent mineral until 1872, around 70 years later, by Albin Weisbach . He discovered it in samples from the “ Weißer Hirsch ” mine near Neustädtel , a district of Schneeberg in the Saxon Ore Mountains, and named it after Gustav Anton Zeuner (1828–1907), the then director of the Freiberg Bergakademie .
classification
In the outdated 8th edition of the mineral classification according to Strunz , zeunerite belonged to the mineral class of "phosphates, arsenates and vanadates" and there to the department of "water-containing phosphates, arsenates and vanadates with foreign anions ", where together with autunit , bassetite , Fritzscheit , Heinrichit , Kahlerit , Kirchheimerit , Natrouranospinit , Nováčekit , Sabugalit , Saléeit , Torbernit ( Uranit ) Uramphit , Uranocircit , Uranospathit , Uranospinit belonging to the family of uranyl phosphates, arsenates and -Vanadate "Uranit-series" with the system number . VII / D.20a .
Metazeunerit together with abernathyite , meta Ankoleit , meta-autunite , Metabassetit ( meta Bassetit ; discredited because identical to Bassetit) Metaheinrichit , Metakahlerit , Metakirchheimerit , Metanatroautunit , Metanatrouranospinit , Metanováčekit , Metatorbernit , Metauramphit , Metauranocircit , Metauranospinit , Sincosit , Trögerite in the following "Meta-Uranite series" with the system no. VII / D.20b .
In the last revised and updated Lapis mineral directory by Stefan Weiß in 2018 , which, out of consideration for private collectors and institutional collections, is still based on this classic systematics by Karl Hugo Strunz , Zeunerite received the system and mineral number. VII / E.01-80 . In the "Lapis system" this corresponds to the section "Uranyl phosphates / arsenates and uranyl vanadates with [UO 2 ] 2+ - [PO 4 ] / [AsO 4 ] 3- and [UO 2 ] 2+ - [V 2 O 8 ] 6- , with isotypic vanadates (Sincosit-R.) ", Where Zeunerite together with Autunit, Fritzscheit, Heinrichit, Kahlerite, Nováčekit, Rauchit , Sabugalit, Saléeit, Trögerite, Torbernit, Uranocircit, Uranospinit, Sodium Autunit ( Natroautunit ) forms the "Autunit Group".
The less water-containing metazeunerite can be found in the following "Meta-Autunit group" with the system and mineral no. VII / E.02-70 .
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and was updated by the International Mineralogical Association (IMA) until 2009, also classifies zeunerite in the category of "uranyl phosphates and arsenates". This is, however, further subdivided according to the molar ratio of uranyl complex (UO 2 ) to phosphate, arsenate or vanadate complex (RO 4 ), so that the mineral according to its composition in the subdivision "UO 2 : RO 4 = 1: 1" can be found where together with Autunit, Heinrichit, Kahlerit, Kirchheimerit, Metarauchit , Nováčekit-I and -II, Saléeit, Torbernit, Uranocircit-I and -II, Uranospinit and Xiangjiangit the "Autunit group" with the system no. 8.EB.05 forms.
Metazeunerit is also in the following "Metaautunit group" with the system no. 8.EB.10 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns zeunerite to the class of "phosphates, arsenates and vanadates" and there in the department of "water-containing phosphates". Here it is together with metazeunerite in the unnamed group 40.02a.14 within the subdivision of “Water-containing phosphates etc., with A 2+ (B 2+ ) 2 (XO 4 ) × x (H 2 O), with (UO 2 ) 2+ ”.
Crystal structure
Zeunerite crystallizes tetragonally in the space group P 4 / nnc (space group no. 126) with the lattice parameters a = 7.18 Å and c = 20.79 Å as well as two formula units per unit cell .
The crystal structure is characterized by uranyl arsenate layers that are parallel to the (001) plane. Arsenic is tetrahedral surrounded by 4 oxygen atoms, the U 6+ octahedral by 6 oxygen atoms. The AsO 4 tetrahedra are linked with UO 6 octahedra over all 4 corners , the UO 6 octahedra over 4 corners with AsO 4 tetrahedra.
These layers are connected by copper ions (Cu 2+ ), which are bound in the c-direction to the oxygen of the uranyl groups. Parallel to the (001) plane, the Cu ions are surrounded by 4 H 2 O molecules in a planar square . Further H 2 O molecules are located between the uranyl arsenate layers and contribute to a balanced distribution of the charges with a complex system of hydrogen bonds.
The less water-containing metazeunerite also crystallizes tetragonally, but in the space group P 4 / n (space group no. 85) with the lattice parameters a = 7.12 Å and c = 17.40 Å as well as two formula units per unit cell.
properties
Due to the arsenic and uranium contained in the mineral, it has a highly toxic effect on the human body . The alpha radiation emitted by the uranium continuously damages the organism and is also carcinogenic . Taking into account the natural series of decay or existing decay products, the specific activity of Zeunerite is given as 80.27 kBq / g (for comparison: natural potassium 0.0312 kBq / g).
Unlike many other uranium glimmer , zeunerite is not fluorescent when exposed to UV radiation . Its dehydrated form metazeunerite, however, fluoresces yellowish green.
morphology
Zeunerite forms right-angled, mostly leafy-tabular, rarely also thick-tabular crystals and scaly aggregates. Crystals also in combination with steep dipyramidal surfaces. The type locality ("Weißer Hirsch" pit near Schneeberg, Saxony) also shows the occurrence of pointed pyramidal crystals.
Education and Locations
Zeunerite forms secondarily in the oxidation zone of arsenic-containing uranium deposits . As accompanying minerals may include, azurite , malachite , Mansfeldit , Olivenit and Skorodit occur.
As a rather rare mineral formation, zeunerite can sometimes be abundant at various sites, but overall it is not very common. A total of around 180 sites are known to date (as of 2013). In addition to its type locality , the "Weißer Hirsch" mine near Neustädtel, the mineral occurred in Germany in many other mines in the Saxon Ore Mountains, such as at Schreckenberg and near Johanngeorgenstadt . Zeunerite was also found in numerous places in the Black Forest such as Freudenstadt , Wittichen and Oberwolfach in Baden-Württemberg; near Rudolfstein (Fichtelgebirge) , Dörrmorsbach and on the Hartkoppe near Sailauf in Bavaria; in the Wingertsberg quarry near Nieder-Ramstadt in Hesse; near Bad Lauterberg and Braunlage in Lower Saxony; near Ellweiler and Imsbach as well as on Königsberg in Rhineland-Palatinate; near Nunkirchen in Saarland and in the uranium deposit in Ronneburg in Thuringia. In many sites, however, Zeunerite has largely been transformed into Metazeunerite.
In Austria, Zeunerite has so far only been found in the municipality of Mühlbach am Hochkönig in Salzburg and on Grasbergjoch near Thierbach (municipality of Wildschönau) in Tyrol.
The only previously known sites in Switzerland are the Wanni Glacier in the Chriegalp Valley (also Kriegalp ), a side valley of the Binntal , and at Les Marécottes in the canton of Valais .
Other locations are in Argentina, Belgium, Brazil, Chile, China, the Democratic Republic of the Congo ( Zaire ), France, Iran, Italy, Japan, Canada, Morocco, Mexico, Norway, Poland, Portugal, Russia, Slovakia, Spain , South Africa, the Czech Republic, Hungary, the United Kingdom (UK) and the United States of America (USA).
Precautions
Due to the toxicity and the strong ionizing radiation of the mineral, mineral samples from Zeunerite should only be kept in dust- and radiation-tight containers, but especially never in living rooms, bedrooms or workrooms. Absorption into the body ( incorporation , ingestion ) should also be prevented in any case and, for safety, direct body contact should be avoided and face masks and gloves should be worn when handling the mineral.
See also
literature
- Andrew J. Locock, Peter C. Burns: Crystal structures and synthesis of the copper-dominant members of the autunite and meta-autunite groups: Torbernite, zeunerite, metatorbernite and metazeunerite . In: The Canadian Mineralogist . tape 41 , 2003, p. 489–502 (English, rruff.info [PDF; 2.5 MB ; accessed on July 19, 2019]).
- Judith Weiss Frondel: Studies of Uranium Minerals (VII): Zeunerite . In: American Mineralogist . tape 36 , 1951, pp. 249–255 (English, minsocam.org [PDF; 449 kB ; accessed on July 19, 2019]).
- A. Weisbach: Communications to Professor HB Geinitz, Freiberg February 9, 1872 . In: New Yearbook for Mineralogy . 1872, p. 206–208 ( rruff.info [PDF; 289 kB ; accessed on July 19, 2019]).
- A. Weisbach: New uranium ores from Neustädtel near Schneeberg . In: Yearbook for the mining and steel industry in the Kingdom of Saxony, treatises . 1873, p. 119–121 ( strahlen.org/tw [PDF; 430 kB ; accessed on July 19, 2019]).
Web links
- Mineral Atlas: Zeunerite (mineral database German, Wiki)
- Zeunerite. In: mindat.org. Hudson Institute of Mineralogy, accessed July 19, 2019 .
- Metazeunerite. In: mindat.org. Hudson Institute of Mineralogy, accessed July 19, 2019 .
- American-Mineralogist-Crystal-Structure-Database - Zeunerite. In: rruff.geo.arizona.edu. Accessed July 19, 2019 .
- American-Mineralogist-Crystal-Structure-Database - Metazeunerite. In: rruff.geo.arizona.edu. Accessed July 19, 2019 .
Individual evidence
- ↑ Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: May 2019. (PDF 1703 kB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, March 2019, accessed May 20, 2019 .
- ↑ 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. 523 (English).
- ^ A b c David Barthelmy: Zeunerite Mineral Data. In: webmineral.com. Accessed July 19, 2019 .
- ↑ a b Zeunerite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 (English, handbookofmineralogy.org [PDF; 64 kB ; accessed on July 19, 2019]).
- ↑ a b c d Zeunerite. In: mindat.org. Hudson Institute of Mineralogy, accessed July 19, 2019 .
- ^ A b 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. 525 (English).
- ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties. Status 03/2018 . 7th, completely revised and supplemented edition. Weise, Munich 2018, ISBN 978-3-921656-83-9 .
- ↑ Ernest H. Nickel, Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF 1703 kB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed April 25, 2019 .
- ^ Metazeunerite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 (English, handbookofmineralogy.org [PDF; 66 kB ; accessed on July 19, 2019]).
- ↑ Localities for Zeunerite. In: mindat.org. Hudson Institute of Mineralogy, accessed July 19, 2019 .
- ↑ List of locations for Zeunerite in the Mineralienatlas and Mindat , accessed on July 17, 2019.