Fourmarierite
| Fourmarierite | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Pb [(UO 2 ) 4 | O 3 (OH) 4 ] • 4H 2 O |
|
Mineral class (and possibly department) |
Oxides and hydroxides |
|
System no. to Strunz and to Dana |
4.GB.25 ( 8th edition : IV / H.07) 09/05/02/01 |
| Crystallographic Data | |
| Crystal system | orthorhombic (pseudohexagonal) |
| Crystal class ; symbol | orthorhombic-pyramidal, mm 2 |
| Space group | Bb 2 1 m (No. 36, position 5) |
| Lattice parameters | a = 13.99 Å ; b = 16.40 Å; c = 14.29 Å |
| Formula units | Z = 8 |
| Frequent crystal faces | {001}, {101}, {111} |
| Physical Properties | |
| Mohs hardness | 3 to 4 |
| Density (g / cm 3 ) | measured: 6.05 and 7.04; calculated: 5.98 |
| Cleavage | perfectly on {001}, good on {100} |
| colour | yellow to golden yellow, orange-red to golden red, carmine red, reddish brown to brown |
| Line color | orange |
| transparency | transparent to translucent |
| shine | Diamond luster |
| radioactivity | very strong |
| Crystal optics | |
| Refractive indices |
n α = 1.85 to 1.865 n β = 1.885 to 1.92 n γ = 1.890 to 1.97 |
| Axis angle | 2V = 50 ° to 55 ° |
| Pleochroism | X = colorless, Y = pale amber yellow, Z = amber yellow |
Fourmarierite is a rare mineral from the mineral class of oxides and hydroxides . It crystallizes in the orthorhombic crystal system with the chemical composition Pb (UO 2 ) O 3 (OH) 4 .
Fourmarierite develops pseudo-hexagonal, tabular crystals up to about two millimeters in size from yellow to golden yellow, orange-red to golden-red to carmine-red or reddish-brown to brown in color and with a diamond-like sheen on the surfaces.
Etymology and history
Fourmarierite was first described by Henri Buttgenbach in 1924 . It is named after Paul Fourmarier , professor of geology at the University of Liège in Belgium . The type mineral is kept at the University of Liège (catalog no. 16871, 16872) and in the Natural History Museum in Paris (catalog no. 124–181).
classification
Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the fourmarierite belonged to the mineral class of "oxides and hydroxides" and there to the division of " uranyl ([UO 2 ] 2+ ) -hydroxides and -hydrates", where he together with Curit , Metavandendriesscheit , Richetit , Sayrit , Spriggit and Vanden Dries Scheit the unnamed group with the system number IV / H.07 formed.
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the IMA, also classifies fourmarierite in the “uranyl hydroxide” division. However, this is further subdivided according to the possible presence of additional cations and the crystal structure, so that the mineral is classified according to its composition in the sub-section “With additional cations (K, Ca, Ba, Pb etc.); with predominantly UO 2 (O, OH) 5 pentagonal polyhedra ”can be found, where it is the only one in the unnamed group 4.GB.25 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns fourmarierite to the class of "oxides and hydroxides" and there in the department of "uranium and thorium-containing oxides". It can be found here in the subsection “Oxides containing uranium and thorium with a cation charge of 6+ that contain Pb or Bi and some water of crystallization or hydroxyl groups”. There he alone forms the unnamed group 09/05/02 .
Crystal structure
Fourmarierite crystallizes orthorhombically in the space group Bb 2 1 m (space group no. 36, position 5) with the lattice parameters a = 13.99 Å , b = 16.40 Å and c = 14.29 Å as well as 8 formula units per unit cell .
properties
Due to its uranium content of up to 64.53%, the mineral is very radioactive . Taking into account the natural series of decay or existing decay products, the specific activity is given as 115.51 k Bq / g (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
Fourmarierite forms as a secondary mineral in uraninite ( uranium dioxide or UO 2 ). It forms parageneses with uraninite, ianthinite , schoepite , becquerelite, billietite , dewindtite , phosphuranylite , Vandendriesscheit , rutherfordin , torbernite , kasolite , curite and goethite .
There are around 50 known sites of fourmarierite.
In Germany , the mineral can be found in Baden-Württemberg , Bavaria and Saxony . In Austria , a site near Mitterberg zu Mühlbach in the St. Johann im Pongau district in the state of Salzburg is known. There are two sites in Switzerland, both of which are in the canton of Valais .
The remaining localities are divided between Australia , China , France , Gabon , India , Canada , Dem. Rep. Congo , Norway , Poland , Russia , Czech Republic , Hungary and the United States of America .
Precautions
Due to the toxicity and the strong radioactivity of the mineral, mineral samples from fourmarierite 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
- CL Christ, JR Clark: Crystal chemical studies of some uranly oxide hydrates . In: American Mineralogist , Vol. 45, 1960, pp. 1026-1061 ( PDF )
Web links
- Mineral Atlas: Fourmarierite
- Database-of-Raman-spectroscopy - Fourmarierite
- American-Mineralogist-Crystal-Structure-Database - Fourmarierit
Individual evidence
- ^ A b c 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. 252 .
- ↑ a b c d e f g h Fourmarierite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 59 , 7 kB )
- ↑ a b c d Mindat - Fourmarierite
- ↑ a b Webmineral - Fourmarierite