Cuprosklodovskite
| Cuprosklodovskite | |
|---|---|
 |
|
| General and classification | |
| other names |
Jachymovite |
| chemical formula | Cu [(UO 2 ) 2 (SiO 3 OH) 2 ] • 6H 2 O |
|
Mineral class (and possibly department) |
Silicates and Germanates |
|
System no. to Strunz and to Dana |
9.AK.10 ( 8th edition : VIII / B.34) 53.03.01.04 |
| Crystallographic Data | |
| Crystal system | triclinic |
| Crystal class ; symbol | triclinic-pinacoidal |
| Room group (no.) | P 1 (No. 2) |
| Lattice parameters |
a = 7.052 Å ; b = 9.267 Å; c = 6.655 Å, α = 109.23 °; β = 89.84 °; γ = 110.01 ° |
| Formula units | Z = 1 |
| Physical Properties | |
| Mohs hardness | 4th |
| Density (g / cm 3 ) | 3.80 |
| Cleavage | good after {100} |
| Break ; Tenacity | uneven |
| colour | light green, grass green |
| Line color | greenish yellow |
| transparency | transparent to translucent |
| shine | Glass gloss, wax gloss to matt |
| radioactivity | very strong |
| Crystal optics | |
| Refractive indices |
n α = 1.654 to 1.655 n β = 1.664 to 1.667 n γ = 1.664 to 1.667 |
| Birefringence | δ = 0.010 to 0.012 |
| Optical character | biaxial negative |
| Pleochroism | X = almost colorless; Y = Z = yellowish green |
The mineral cuprosklodovskite (in older sources also jachymovite ) is a rather seldom occurring uranium mineral with the chemical composition Cu [(UO 2 ) 2 (SiO 3 OH) 2 ] · 6H 2 O. It crystallizes in the triclinic crystal system and develops mostly acicular, radial-rayed ones grass-green crystals .
Etymology and history
Cuprosklodovskite was first described in 1933 by the Belgian mineralogist Johannes Franciscus Vaes (1902–1978) on a mineral sample from Katanga (then Belgian Congo ) as a variant of the Sklodovskite . Buttgenbach finally named the mineral found by Vaes on the erroneous assumption that it was actually the structural copper analogue of Sklodowskite, which in turn was named in honor of Marie Sklodowska-Curie . In 1935 it was described independently by Radim Nováček on a sample from Jáchymov (St. Joachimsthal), who named it Jachymovite after the place where it was found. The identity of both mineral samples was recognized a short time later by Nováček (1935) and Valère Louis Billiet (1936).
The type mineral is located at the University of Liège (catalog no. 16.655) in Belgium .
The older name Jachymovite should not be confused with the basic uranyl sulfate Jáchymovite, which has been recognized since 1996 .
classification
The outdated 8th edition of the Strunz lists the Cuprosklodowskit in the "Uranophangruppe" with the system no. VIII / B.34 and the other members Boltwoodite , Kasolite , Natroboltwoodite , Oursinite , Sklodovskite , Uranophane and Uranophane-beta .
The 9th, completely revised edition of Strunz lists the cuprosklodovskite in the section K "Uranyl island and sheet silicates with a uranium: silicon ratio of U: Si = 2: 1" in group 9.AK.10 . This group also includes Oursinite and Sklodovskite.
The systematics of minerals according to Dana , which is common in the English-speaking world , assigns the cuprosklodovskite to the uranophane group of the island silicates department, but there in the department of " island silicates with SiO 4 groups and other anions as well as complex cations with (UO 2 ) " with the system No. 53.03.01.04 a.
Crystal structure
Cuprosklodovskite crystallizes in the triclinic space group P 1 (space group no. 2) with the lattice parameters a = 7.052 Å ; b = 9.267 Å; c = 6.655 Å with α = 109.23 ° β = 89.84 ° and γ = 110.01 ° as well as one formula unit per unit cell .
Packing pattern of cuprosklodovskite in the direction of the crystallographic a -axis ( __ U __ O __ Si __ Cu __ water molecules )
Packing pattern of cuprosklodovskite in the direction of the crystallographic b -axis ( __ U __ O __ Si __ Cu __ water molecules )
Packing pattern of cuprosklodovskite in the direction of the crystallographic c axis ( __ U __ O __ Si __ Cu __ water molecules )
The basic structure of the cuprosklodovskite consists of layers of chain-shaped, edge-linked pentagonal-bipyramidal uranyl units, the equatorial oxygen atoms of which are each connected by tetrahedrally coordinated silicon atoms . The silicon atoms coordinate three uranyl units; the fourth binding site is saturated by a hydroxide ion . The Cu 2+ ion connects two adjacent layers by bridging two oxygen atoms from opposing uranyl units (∠ (UO-Cu) = 142.38 °, ∠ (O-Cu-O) = 180 °). Although chemical analysis suggests describing cuprosklodovskite as a copper analogue of sclodovskite , this is incorrect from a crystallographic point of view. The differences in the crystal system (triclinic vs. monoclinic) as well as the different connection of the uranyl-silicate layers by the divalent cations (Cu 2+ vs. Mg 2+ ) clearly show that these two minerals differ from each other more than the name initially suggests leaves.
properties
The mineral is radioactive due to its uranium content of over 55% . Taking into account the proportions of the radioactive elements in the idealized empirical formula and the subsequent decays of the natural decay series, a specific activity of about 98.9 k Bq / g is specified for the mineral (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
Cuprosklodovskite occurs in the weathering zone of primary uranium ores. It is found in association with Becquerelit , Brochantit , Uranophan , Kasolit , Vandenbrandeit , Liebigit and Compreignacit . Its type locality is Kalongwe in the Democratic Republic of the Congo , where it was found in the mines of Musonoi and Shinkolobwe , as well as in Kasompi , Luiswishi and Kamoto . In Germany it is known from the Krunkelbach mine , but there it is extremely rare. Other locations in Germany are Schneeberg , Wölsendorf and Sailauf . It was also found in Jáchymov and Zálesí in the Czech Republic and in Rabejac near Lodève in France. Other sites are Port Radium District (Canada), Utah and New Mexico (USA) as well as individual sites in Italy, Great Britain, Japan, Poland, Spain and Switzerland.
Precautions
Due to the toxicity and radioactivity of the mineral, mineral samples from cuprosklodovskite 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
- Paul Ramdohr , Hugo Strunz : Klockmann's textbook of mineralogy . 16th edition. Ferdinand Enke Verlag, 1978, ISBN 3-432-82986-8 , pp. 687 .
- Cuprosklodowskite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 73.6 kB )
- Petr Korbel, Milan Novák: Encyclopedia of Minerals . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 210 .
Web links
Individual evidence
- ↑ a b c d A. Rosenzweig, RR Ryan: Refinement of the crystal structure of cuprosklodowskite, Cu [(UO 2 ) 2 (SiO 3 OH) 2 ] · 6H 2 O In: American Mineralogist 1975, 60, p. 448– 453. (English, PDF, 635 kB)
- ↑ a b c d e Webmineral - Cuprosklodowskite (English)
- ↑ a b Mindat - Cuprosklodowskite (English)
- ↑ The Minerals of the Democratic Republic of Congo at euromin.w3sites.net ( Memento of the original from May 29, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
-
↑
JP Vaes: Sur un minéral de Kalongwe (Katanga) in: Annales de la Société Géologique de Belgique , 1933, Bull. 10, 56, pp. 331-332. (French, PDF, 172 kB)
Note: The abbreviation JP Vaes is most likely a typographical error, see also the reference list for the mineral description of Cuprosklodowskite in Sergey V. Krivovichev: Minerals as Advanced Materials II Springer Science & Business Media, 2011, p. 166 in Google Book search - ↑ a b FV Stohl, DK Smith, The crystal chemistry of the uranyl silicate minerals In: American Mineralogist 1981, 66, pp. 610–625 ( PDF 1.6 MB (English))
- ↑ Cuprosklodowskite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 73.6 kB )
