Billietit
| Billietit | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Ba [(UO 2 ) 6 | O 4 | (OH) 6 ] • 8H 2 O |
|
Mineral class (and possibly department) |
Oxides and hydroxides |
|
System no. to Strunz and to Dana |
4.GB.10 ( 8th edition : IV / H.03) 07/05/01/03 |
| Crystallographic Data | |
| Crystal system | orthorhombic |
| Crystal class ; symbol | orthorhombic-pyramidal; mm 2 |
| Room group (no.) | Pbn 2 1 (No. 33) |
| Lattice parameters |
a = 12.07 Å ; b = 30.16 Å; c = 7.14 Å β = 123.36 ° |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | Please complete |
| Density (g / cm 3 ) | measured: 5.27 to 5.29 |
| Cleavage | completely according to {001}, uneven according to {110} and {010} |
| Break ; Tenacity | brittle |
| colour | yellow-brown, golden brown, orange-yellow, amber-yellow |
| Line color | yellow |
| transparency | transparent to translucent |
| shine | Diamond luster |
| radioactivity | very strong |
| Crystal optics | |
| Refractive indices |
n α = 1.725 to 1.735 n β = 1.815 to 1.825 n γ = 1.825 to 1.830 |
| Birefringence | δ = 0.065 to 0.099 |
| Optical character | biaxial negative |
| Axis angle | 2V = measured: 36 ° |
| Pleochroism | Visible: X = colorless to pale yellow, Y = Z = green yellow to deep golden yellow, amber brown |
Billietite is a rarely occurring uranium mineral from the mineral class of " oxides and hydroxides ". It crystallizes in the orthorhombic crystal system with the chemical composition Ba [(UO 2 ) 6 | O 4 | (OH) 6 ] · 8H 2 O and develops mostly translucent, prismatic and pseudo-hexagonal crystals of yellow-brown to amber-brown color with a yellow streak . A diamond-like sheen appears on the crystal surfaces . Star-shaped aggregates formed by triplet formation are typical for the mineral. From a chemical point of view, it is a hydrated barium uranyl oxide.
Etymology and history
Billietite was first described in 1947 by the Belgian mineralogist Johannes Franciscus Vaes , who named it in honor of the Belgian mineralogist Valère Louis Billiet (born February 14, 1903 in Ghent). Billiet was active in the French resistance, captured on August 10, 1944, and finally murdered by the SS shortly before the end of the war on a prisoner transport.
There are two type minerals, one of which is at Harvard University (Catalog No. 104455) in Cambridge, Massachusetts, USA and another at the National Museum of Natural History (Catalog No. 160496), Washington, DC, USA.
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the billietite belonged to the mineral class of "oxides and hydroxides" and there to the department of "uranyl hydroxides and hydrates", where together with Becquerelit , Compreignacit , Masuyit and Protasit formed an independent group.
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns billietite to the class of "oxides and hydroxides" and there in the department of "uranyl hydroxides". However, this section is further subdivided according to the presence of further cations and the crystal structure, so that the mineral is classified according to its composition and structure in the sub-section “With additional cations (K, Ca, Ba, Pb etc.), with predominantly UO 2 (O , OH) 5 pentagonal polyhedra "can be found in the" Becquerelite group "(system no. 4.GB.10 ) together with the namesake Becquerelite and Protasite.
The systematics of minerals according to Dana also assigns billietite to the class of "oxides and hydroxides", but there in the department of "uranium and thorium-containing oxides". Here he is also in the "Becquerelite group" with the system no. 05.07.01 to be found together with Compreignacit and Becquerelit within the sub-section of " Oxides containing uranium and thorium with alkali or hydrated hydroxide components ".
Crystal structure
Billietite crystallizes in the orthorhombic crystal system in the space group Pbn 2 1 with the lattice parameters a = 12.07 Å , b = 30.16 Å, c = 7.14 Å and β = 123.36 ° as well as four formula units per unit cell .
In the crystal structure , the uranium atom has a pentagonal-bipyramidal geometry. Through the coordination of oxygen atoms, these form two types of layers of edge-linked and corner-linked uranyl polyhedra. The first type corresponds to the layers in the structures of ianthinite and wyartite . The second type corresponds to the layers in the structures of protasite , compreignacite and becquerelite . These layers alternate along the crystallographic b-axis and are linked by barium atoms. The barium atom is coordinated by six uranyl oxygen atoms (2.77 to 2.99 Å apart) and four water molecules (2.77 to 2.86 Å apart). This coordination is similar to that of barium in the minerals guilleminite and protasite.
properties
The mineral is by its uranium content of up to 69.1 wt .-% as highly radioactive classified and has a specific activity of about 123.6 k Bq / g (compared to natural potassium 0.0312 kBq / g).
Education and Locations
Billietite is found as a rare transformation product in the oxidation zone of primary uranium ore deposits. Depending on where it was found, the mineral is associated with uranophane , fourmarierite , rutherfordin , becquerelite , studtite , sodyite and torbernite .
In addition to the type locality in Shinkolobwe, billietite was also found in the Swambo mine. From Germany, billietite is known from the Krunkelbach mine near Menzenschwand , from Wittichen (Sophia mine), from the Heubachtal (Anton mine) and Oberwolfach (Clara mine) and from Bergen in Saxony. In Switzerland it was found in the canton of Valais in the Eifisch valley and the Trient valley . Other locations are in Alsace in France the uranium deposit Kruth 2 and in the Occitania region in the Hérault department in Rabejac near Lodève . In Italy it was found in Val Rendena, in the USA in the Picks Delta Mine in Utah and in Australia in the Radium Ridge. Other locations are the Lianshanguan Mine in China, Labská dam, Moldava (Moldawa) and Slavkovice in the Czech Republic, the Eureka Mine in Spain and the Åsnebo Mine in Sweden.
use
Due to the barium content of billietite, which occurs as a fissile element in nuclear waste, it is suitable as an object of investigation for the oxidation of spent nuclear fuel in groundwater, for the incorporation of different radionuclides in hydrated uranyl oxides and for mobility studies of radioactive waste.
Precautions
Due to the strong radioactivity of the mineral, mineral samples from billietite should only be kept in dust- and radiation-tight containers, but above all never in living rooms, bedrooms or workrooms. Likewise, because of the high toxicity and radioactivity of uranyl compounds, absorption into the body ( incorporation , ingestion ) should 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
- Billietite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 70.9 kB )
Web links
- Mineral Atlas: Billietite
- Photos of Billietit on the website of the Association des Géologues Amateurs de Belgique (AGAB)
Individual evidence
- ↑ a b Billietite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 66.9 kB )
- ↑ a b c Billietite at Webmineral.com
- ↑ a b c d e RL Finch, PC Burns, FC Hawthorne, RC Ewing: (2006) "Refinement of the crystal structure of billietite, Ba [(UO 2 ) 6 O 4 (OH) 6 ] (H 2 O) 8 "In:" The Canadian Mineralogist "2006, 44, 1197–1205 ( PDF (English) 1.8 MB )
- ↑ a b c Mindat - Billietite
- ^ JF Vaes: Six nouveaux minéraux d'urane provenant de Shinkolobwe (Katanga) , In: Annales de la Société Géologique de Belgique. 1947, pp. B212 to B226 ( PDF (French) 441 kB )
- ↑ M. Fleischer: "New mineral names", In: "American Mineralogist" 1948, 33, 384–386 ( PDF (English) 176 kB )