Grimselit
| Grimselit | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 1971-040 |
| chemical formula | K 3 Na [UO 2 | (CO 3 ) 3 ] • H 2 O |
|
Mineral class (and possibly department) |
Carbonates and nitrates (formerly carbonates, nitrates and borates) |
|
System no. to Strunz and to Dana |
5.ED.35 ( 8th edition : V / F.02) 02/15/06/01 |
| Crystallographic Data | |
| Crystal system | hexagonal |
| Crystal class ; symbol | ditrigonal-dipyramidal; m 2 |
| Room group (no.) | P 6 2 c (No. 190) |
| Lattice parameters | a = 9.30 Å ; c = 8.26 Å |
| Formula units | Z = 2 |
| Frequent crystal faces | {10 1 O}, {10 1 l}, {0001} |
| Physical Properties | |
| Mohs hardness | 2 to 2.5 |
| Density (g / cm 3 ) | measured: 3.30 (synthetic); calculated: 3.27 |
| Cleavage | Please complete |
| Break ; Tenacity | clamshell; brittle |
| colour | yellow |
| Line color | light yellow |
| transparency | transparent to translucent |
| shine | Glass gloss |
| radioactivity | very strong |
| Crystal optics | |
| Refractive indices |
n ω = 1.601 n ε = 1.480 |
| Birefringence | δ = 0.121 |
| Optical character | uniaxial negative |
| Other properties | |
| Chemical behavior | water soluble |
Grimselite is a very rare mineral from the mineral class of " carbonates and nitrates " (formerly "carbonates, nitrates and borates "). It crystallizes in the hexagonal crystal system with the chemical composition K 3 Na [UO 2 | (CO 3 ) 3 ] · H 2 O and is thus chemically a water-containing potassium - sodium - uranyl carbonate .
Grimselit only develops tiny crystals up to about 0.3 millimeters in diameter with a hexagonal tabular to prismatic habit . It is mostly found in the form of leafy or granular mineral aggregates and crusty coatings. The predominantly yellow, rarely greenish-yellow crystals are transparent to translucent and show a glass-like sheen on the crystal surfaces . Grimselit leaves a light yellow line on the whiteboard .
Etymology and history
Grimselit was first found in 1969 by Kurt Walenta on the Grimsel Pass between the Bernese Oberland and Upper Valais on the construction site for the Oberhasli power plant in Switzerland. HA Stalder later found more pieces that allowed a more detailed analysis. Walenta chose its type locality as the name giver for the mineral and submitted its test results to the International Mineralogical Association (IMA) for examination in 1971 (register no. IMA 1971-040 ).
Type material of the mineral is kept in the Institute for Mineralogy and Crystal Chemistry of the University of Stuttgart and in the State Museum for Natural History Stuttgart .
classification
In the outdated, but partly still in use, 8th edition of the mineral classification according to Strunz , the grimselite belonged to the common mineral class of "carbonates, nitrates and borates" and there to the division of " uranyl carbonates [UO 2 ] 2+ to [CO 3 ] 2− " , where together with Andersonite , Bayleyite , Čejkait , Fontanite , Liebigite , Metazellerite , Swartzite and Zellerite , it formed the unnamed group V / F.02 .
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 the Grimselite to the newly defined class of "carbonates and nitrates", but also to the category of "uranyl carbonates" there. However, this is further subdivided according to the molar ratio of uranyl to carbonate complex, so that the mineral can be found according to its composition in the sub-section "UO 2 : CO 3 = 1: 4", where it is the only member of the unnamed group 5.ED .35 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Grimselit to the common class of "carbonates, nitrates and borates" and there in the department of "hydrous carbonates", like the outdated Strunz system. Here he is the only member of the unnamed group 02/15/06 within the subdivision “ Hydrogen carbonates with A + m B 2+ n (XO 3 ) p • x (H 2 O), (m + n): p> 1: 1 ”.
Crystal structure
Grimselite crystallizes hexagonally in the space group P 6 2 c (space group no. 190) with the lattice parameters a = 9.30 Å and c = 8.26 Å as well as two formula units per unit cell .
properties
Grimselit is water-soluble, whereby the solution reacts alkaline.
Due to its uranium content of up to 39.13%, the mineral is very radioactive . Taking into account the natural decay chains or of existing decay products which is specific activity of 70.043 k Bq / g indicated (compared to natural potassium 0.0312 kBq / g).
Education and Locations
Grimselit comes as a rare secondary mineral in interspersed passages of granodiorites and aplite - granites ago, where he mostly quartz and feldspar can be found astride. As accompanying minerals may include Bayleyit , Baylissit , calcite , Čejkait , Monohydrocalcit and schröckingerite occur.
As a very rare mineral formation, Grimselite could so far (as of 2014) only be detected in a few samples from less than 10 sites. In addition to its type locality Gerstenegg-Sommerloch Tunnel and the nearby NAGRA in Switzerland, the only known sites are the uranium deposit in the Krunkelbachtal near the municipality of Menzenschwand in the German state of Baden-Württemberg as well as the Rovnost Mine ( Werner Mine ) and Svornost Mine ( Unity Mine ) near Jáchymov ( Sankt Joachimsthal ) in the Czech region of Bohemia.
Precautions
Due to the toxicity and the strong radioactivity of the mineral, mineral samples from Grimselit should only be kept in dust- and radiation-proof 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
- Kurt Walenta : Grimselite, a new Ka-Na-uranyl carbonate from the Grimsel region, Oberhasli, Bern canton, Switzerland. In: Schweizerische Mineralogische und Petrographische Mitteilungen = Bulletin Suisse de Mineralogie et Petrographie Volume 52-1 (1972), pp. 93-108
- Carl Hintze : Handbook of Mineralogy . New minerals and new mineral names (with addenda, corrections and additions). Supplementary volume 4, part 2. Walter de Gruyter, Berlin 1975, ISBN 3-11-005850-2 , p. 283–285 ( limited preview in Google Book search).
- Yaping Li, Peter C. Burns (2001): The crystal structure of synthetic Grimselite, K 3 Na [(UO 2 ) (CO 3 ) 3 ] (H 2 O) In: The Canadian Mineralogist Volume 39, No. 4, p 1147–1151 doi : 10.2113 / gscanmin.39.4.1147
- Philippe Roth: Minerals First Discovered in Switzerland and Minerals Named After Swiss Individuals. Excalibur Mineral Corp. 2007, ISBN 978-3-9807561-8-1 , pp. 78–79 ( limited preview in Google book search)
Web links
Individual evidence
- ↑ a b c d e Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 321 .
- ↑ a b c d e Grimselite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 74 kB )
- ↑ a b Mindat - Grimselite
- ^ Philippe Roth: Minerals First Discovered in Switzerland and Minerals Named After Swiss Individuals. Excalibur Mineral Corp. 2007, ISBN 978-3-9807561-8-1 , pp. 78–79 ( limited preview in Google book search)
- ↑ Type material catalog of the University of Hamburg - Grimselit
- ↑ Carl Hintze: Handbook of Mineralogy . New minerals and new mineral names (with addenda, corrections and additions). Supplementary volume 4, part 2. Walter de Gruyter, Berlin 1975, ISBN 3-11-005850-2 , p. 284 ( limited preview in Google Book search).
- ↑ Webmineral - Grimselite
- ↑ Find location list for grimselite in the Mineralienatlas and Mindat