Curienite

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Curienite
Curienite-Francevillite-rad08-12b.jpg
Curienite (yellow) and Francevillit (orange) from the Mounana Mine (Mouana Mine), Franceville , Haut-Ogooué, Gabon
General and classification
other names

IMA 1967-049

chemical formula Pb [UO 2 | VO 4 ] 2 • 5H 2 O
Mineral class
(and possibly department) 		Oxides and hydroxides (formerly phosphates, arsenates and vanadates)
System no. to Strunz
and to Dana 		4.HB.15 ( 8th edition : VII / E.11)
40.02a.27.02
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol orthorhombic-dipyramidal; 2 / m 2 / m 2 / m
Room group (no.) Pcan (No. 60)
Lattice parameters a  = 10.40  Å ; b  = 8.45 Å; c  = 16.34 Å
Formula units Z  = 4
Physical Properties
Mohs hardness 3
Density (g / cm 3 ) measured: 4.88; calculated: 4.94
Cleavage Please complete!
colour canary yellow
Line color light yellow
transparency translucent
shine Diamond luster, pearlescent luster
radioactivity very strong
Crystal optics
Refractive indices n α  unknown 
n β  > 2
n γ  > 2
Optical character biaxial negative
Axis angle 2V = 66 °

Curienite is a rarely occurring mineral from the mineral class of " oxides and hydroxides " (formerly phosphates, arsenates and vanadates ). It crystallizes in the orthorhombic crystal system with the chemical composition Pb [UO 2 | VO 4 ] 2 · 5H 2 O and develops only microcrystalline mineral aggregates of canary yellow color with light yellow streak color .

With Francevillit (Ba [UO 2 | VO 4 ] 2 · 5H 2 O) curienite forms a complete mixed crystal series.

Etymology and history

Curienite was first discovered in the "Mounana Mine" near Franceville in Gabon and described in 1968 by Fabien Cesbron and Noël Morin , who named the mineral after the French research minister and physicist Hubert Curien (1924-2005).

The spelling Curiénit , originally chosen by Cesbron and Morin , has been discredited since 2008 because the namesake is written without an acute accent over the 'e' and is therefore an unnecessary diacritical mark .

classification

In the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the curienite belonged to the mineral class of " phosphates , arsenates and vanadates " and there to the department of "uranyl phosphates / arsenates and uranyl vanadates ", where it belonged together with carnotite , Francevillit , margaritasite , Metatyuyamunit , Metavanuralit , Sengierit , Strelkinit , Tyuyamunit and Vanuranylit the group of the "Uranyl group vanadates with [UO 2 ] 2+ - [V 2 O 8 ] 6− " with the system no. VII / E.11 formed.

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 curienite to the class of "oxides and hydroxides" and there in the department of "V [5,6] vanadates" . This is further subdivided according to the crystal structure, so that the mineral can be found in the sub-section "Uranyl group vanadate (Sorovanadate)" according to its structure, where, together with Francevillit and Fritzscheit, the "Francevillit group" with the system no. 4.HB.15 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking area , assigns the curienite to the class of "phosphates, arsenates and vanadates", like the outdated Strunz'sche systematics, but there in the category of "water-containing phosphates etc.". Here he is together with Francevillit in the unnamed group 40.02a.27 within the subdivision “Water-containing phosphates etc., with A 2+ (B 2+ ) 2 (XO 4 ) × x (H 2 O), with (UO 2 ) 2+ ”can be found.

Crystal structure

Curienite crystallizes isotypically with Francevillit in the orthorhombic crystal system in the space group Pcan (space group no. 60) with the lattice parameters a  = 10.40  Å ; b  = 8.45 Å and c  = 16.34 Å and 4 formula units per unit cell .

properties

The mineral is classified as highly radioactive due to its uranium content of up to 44.6% and has a specific activity of about 79.8 k Bq / g (for comparison: natural potassium 31.2 Bq / g).

Education and Locations

Curienit formed in the oxidation zone of lead-containing uranium - vanadium - deposits . Accompanying minerals in addition to Francevillite are other uranium minerals such as carnotite , dewindtite , johannite , kasolite , metatorbernite , torbernite , uraninite , uranopilite , vanuralite and zeunerite , but also chervetite , duttonite , galenite , mottramite , sphalerite and quartz .

As a rare mineral formation, curienite could only be detected at a few sites, whereby so far (as of 2013) a little more than 10 sites are known. In addition to its type locality "Mounana Mine", the mineral was found in Gabon in several other mines around Franceville .

The only previously known site in Germany is St. Ulrich in the Black Forest (moat, passage no. 6) in Baden-Württemberg. In addition, Curienit occurred at Shinkolobwe in the Democratic Republic of the Congo, Échassières ( Canton Gannat ) and Saint-Martin-de-Belleville ( Département Savoie ) in France, at the Akashat phosphate deposit in Iraq , and the prospected uranium deposit Rio Giulis near Condino in the autonomous province Trentino and near Sankt Joachimsthal in the Czech Republic.

Precautions

Due to the strong radioactivity of the mineral, mineral samples of curienite should only be kept in dust-tight and radiation-tight 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

Web links

Commons : Curienite  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b c d e f 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.  256 .
  2. ↑ a b Webmineral - Curienite (English)
  3. ↑ a b c Curienite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 66 kB )
  4. ^ Ernst AJ Burke: Tidying up Mineral Names: an IMA-CNMNC Scheme for Suffixes, Hyphens and Diacritical marks , In: Mineralogical Record , Volume 39, No. 2 (March – April 2008); PDF 2.7 MB
  5. ↑ Find location list for curienite at the Mineralienatlas and at Mindat