Wölsendorfite

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Wölsendorfite
General and classification
chemical formula Pb 7 [(UO 2 ) 14 | O 19 | (OH) 4 ] • 12H 2 O
Mineral class
(and possibly department) 		Oxides and hydroxides
System no. to Strunz
and to Dana 		4.GB.30 ( 8th edition : IV / H.06)
04/05/03/02
Similar minerals Calciouranoite , metacalciouranoite , bauranoite
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol rhombic-dipyramidal 2 / m 2 / m 2 / m (short symbol: mmm )
Space group Cmcm
Lattice parameters a  = 14.13  Å ; b  = 13.88 Å; c  = 55.97 Å
Formula units Z  = 8
Physical Properties
Mohs hardness 5
Density (g / cm 3 ) 6.8
Cleavage good after {001}
colour orange red, carmine red
Line color not defined
transparency translucent
shine Glass gloss to diamond gloss
radioactivity highly radioactive
Crystal optics
Refractive indices n α  = 2.050
n γ  = 2.090
Birefringence δ = 0.040
Optical character biaxial

Wölsendorfite is a rarely occurring mineral from the mineral class of " oxides and hydroxides ". It crystallizes in the orthorhombic crystal system with the chemical composition Pb 7 [(UO 2 ) 14 | O 19 | (OH) 4 ] • 12H 2 O and develops tabular crystals of a few millimeters in size, but also spherical mineral aggregates or crusty coatings of orange-red to deep carmine color.

Etymology and history

Wölsendorfite was first discovered in 1957 in the Johannesgang of the "Johannes mine" near Wölsendorf in the municipality of Schwarzach near Nabburg (Schwandorf district, Bavaria) in Germany and described by Jean Protas (* 1932), a French mineralogist and professor at the University of Nancy , who wrote the Mineral named after its type locality Wölsendorf.

classification

In the meanwhile outdated system of minerals according to Strunz (8th edition) the wölsendorfite still belongs to the common division of "uranyl hydroxides and hydrates", where it forms a separate group together with bauranoite , calciouranoite and metacalciouranoite .

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” section and there in the “With additional cations (K, Ca, Ba, Pb etc.) sub-section; with predominantly UO 2 (O, OH) 5 pentagonal polyhedra ”, where he is the only member of the unnamed group 4.GB.30 .

The systematics of minerals according to Dana , which is common in the English-speaking world , also assigns the wölsendorfite to the class of oxides, but there in the division of " uranium and thorium-containing oxides containing alkaline earth metal elements (hydrous) ", where it is the unnamed together with metacalciouranoite Group 04/05/03 forms.

Crystal structure

Wölsendorfite crystallizes orthorhombically in the space group Cmcm with the lattice parameters a  = 14.13  Å ; b  = 13.88 Å and c  = 55.97 Å as well as eight formula units per unit cell .

properties

The mineral is radioactive due to its uranium content of up to 59.99% . Taking into account the natural decay chains or of existing decay products which is specific activity with k 107.38 Bq / g indicated (compared to 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.

Education and Locations

Wölsendorfite is secondary to the weathering of uraninite in the oxidation zone of uranium-containing deposits . Accordingly, it occurs mainly in paragenesis with uraninite, but also with becquerelite , kasolite , masuyite , metastudtite and rutherfordin .

So far (as of 2010) Wölsendorfite has been detected at almost 40 sites worldwide, for example in the Koongarra deposit in the Northern Territory of Australia; in the “Urucum Mine” near Galiléia in the Brazilian state of Minas Gerais ; in Baden-Württemberg , Bavaria and Saxony in Germany; some French regions; in the "Oklo Mine" near Franceville in Gabon; in the area around Randboldal in the Greenland region of Avanersuaq (Avannaa, Danish: Nordgrønland); near Bocenago in Val Rendena in the Italian province of Trentino ; at Port Radium on Great Bear Lake in Canada; in the " Shinkolobwe Mine" in the Congolese province of Katanga ; in the Norwegian municipality of Tokke ; near Krasnokamensk in Russia; in the Swedish regions of Lapland , Södermanland and Värmland ; in some regions of the Czech Republic ; in the "Botallack Mine" of the St Just mining district, Cornwall in the United Kingdom (Great Britain) and in the US regions of Colorado , Maine and Pennsylvania .

Precautions

Due to the toxicity and the strong radioactivity of the mineral, absorption into the body (orally) should be prevented in any case and direct body contact should be avoided for safety and face mask and gloves should be worn when handling the mineral.

See also

Individual evidence

  1. ↑ a b c Webmineral - Wolsendorfite (English)
  2. ^ A b 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 .
  3. ↑ a b c Wölsendorfite at mindat.org (engl.)
  4. ↑ Stefan Weiß: The large Lapis mineral directory . 5th edition. Christian Weise Verlag, Munich 2008, ISBN 3-921656-17-6 .
  5. ↑ IMA / CNMNC List of Mineral Names - Wölsendorfite (English, PDF 1.8 MB; p. 307)
  6. ↑ Mindat - Protasite
  7. ^ 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 .

literature

Web links