Vandenbrandeit
| Vandenbrandeit | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Cu [UO 2 | (OH) 4 ] |
|
Mineral class (and possibly department) |
Oxides and hydroxides |
|
System no. to Strunz and to Dana |
4.GB.45 ( 8th edition : IV / H.04) 05.03.02.01 |
| Crystallographic Data | |
| Crystal system | triclinic |
| Crystal class ; symbol | triclinic pinacoidal; 1 |
| Space group | P 1 (No. 2) |
| Lattice parameters |
a = 7.855 Å ; b = 5.449 Å; c = 6.089 Å, α = 91.44 °; β = 101.90 °; γ = 89.2 ° |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 4th |
| Density (g / cm 3 ) | 4.91 to 5.03 |
| Cleavage | completely after {001} |
| colour | dark green, black green |
| Line color | green |
| transparency | transparent to translucent |
| shine | Glass gloss |
| radioactivity | highly radioactive |
| Crystal optics | |
| Refractive indices |
n α = 1.760 to 1.770 n β = 1.780 to 1.792 n γ = 1.800 |
| Birefringence | δ = 0.040 |
| Optical character | biaxial negative |
| Axis angle | 2V = measured: 90 °; calculated: 60 to 88 ° |
| Pleochroism | yellow-green to blue-green |
Vandenbrandeite is a rarely occurring mineral from the mineral class of " oxides and hydroxides ". It crystallizes in the crystal system with the chemical composition Cu [UO 2 | (OH) 4 ] and develops mostly transparent to translucent, thin, tabular to leafy crystals (often composed in parallel layers), but also massive aggregates of dark green to black-green color and green Line color.
Etymology and history
The Vandenbrandeit was found for the first time in a uranium ore - deposit in Kalongwe in Katanga (DRC) and described in 1932 by Alfred Schoep (1881-1966), of the minerals by Pierre Van den Brande called, the Belgian geologist and soil expert of Katanga, the discovered the deposit in Kalongwe.
classification
In the old systematics of minerals according to Strunz (8th edition) , the Vandenbrandeit still belongs to the common division of "uranyl hydroxides and hydrates". With the revision of Strunz's mineral systematics in the 9th edition , this department was divided up and also more precisely divided according to the type of cations involved and the crystal structure. The mineral is now in the “Uranyl Hydroxide” department and there as the only one of its group in the “With additional cations (K, Ca, Ba, Pb etc.); with predominantly UO 2 (O, OH) 5 pentagonal polyhedra ”.
The systematics of minerals according to Dana , which is common in the English-speaking world , also assigns the Vandenbrandeit to the class of oxides, but there in the division of " uranium and thorium-containing oxides with a cation charge of 8+ (AO 4 ), also hydrated ".
Crystal structure
Vandenbrandeit crystallizes in the triclinic crystal system in the space group P 1 (space group no. 2) with the lattice parameters a = 7.855 Å ; b = 5.449 Å; c = 6.089 Å; α = 91.44 °; β = 101.90 ° and γ = 89.2 ° as well as two formula units per unit cell .
properties
The mineral is radioactive due to its uranium content of up to 59.27% . 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 106 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
Vandenbrandeite forms secondarily in the oxidation zone of copper-containing uranium deposits and occurs there mainly in paragenesis with cuprosklodovskite and kasolite , but also with chalcosine , chalcopyrite , curite , goethite , malachite , sharpit , sklodovskite , uraninite and uranophane .
Vandenbrandeit has so far been found at 10 sites worldwide (as of 2009): Near Lodève in France; at St Just in Penwith (England); next to its type locality Kalongwe also near Lubumbashi , Kambove , Kamoto , Kolwezi , Shinkolobwe and Swambo in the Democratic Republic of the Congo; as well as (with reservation) at Nové Město na Moravě (Moravia) in the Czech Republic.
Precautions
Due to the toxicity and the strong radioactivity of the mineral, mineral samples from Vandenbrandeit should only be kept in dust and radiation-proof 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 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. 560 .
Web links
- Mineral Atlas: Vandenbrandeit (Wiki)
- Photos by Vandenbrandeit on the website of the Association des Géologues Amateurs de Belgique (AGAB)
Individual evidence
- ↑ a b c d Webmineral - Vandenbrandeite (English)
- ↑ a b American Mineralogist Crystal Structure Database - Vandenbrandeite (English, 1977)
- ↑ a b c Vandenbrandeite at mindat.org (engl.)
- ↑ American Mineralogist Structure Database - Vandenbrandeite (English, 1977)
- ↑ Mindat - Localities for Vandenbrandeite