Calciouranoite

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Calciouranoite
General and classification
other names

IMA 1973-004

chemical formula (Ca, Ba, Pb) [(UO 2 ) 2 | O 3 ] • 5H 2 O
Mineral class
(and possibly department) 		Oxides (uranyl hydroxides and hydrates)
System no. to Strunz
and to Dana 		4.GB.20 ( 8th edition : IV / H.06)
04/05/02/01
Similar minerals Metacalciouranoite , bauranoite , wölsendorfite
Crystallographic Data
Crystal system triclinic, metamictic amorphous
Physical Properties
Mohs hardness 4th
Density (g / cm 3 ) 4.62
Cleavage Please complete!
colour red-orange, yellow-brown, orange-brown, brown
Line color unknown
transparency translucent
shine Greasy to matt
radioactivity highly radioactive
Crystal optics
Refractive indices n α  = 1.760
n β  = 1.840
n γ  = 1.870
Birefringence δ = 0.110
Optical character biaxial negative
Other properties
Special features toxic

Calciouranoite is a very rarely occurring mineral from the mineral class of " oxides and hydroxides ". It crystallizes in the triclinic crystal system with the chemical composition (Ca, Ba, Pb) [(UO 2 ) 2 | O 3 ] · 5H 2 O and develops prismatic to needle-like crystals , but also radial-fiber to spherical mineral aggregates of red- orange, yellow-brown, orange-brown or brown color.

Etymology and history

Was first discovered in 1974 in Calciouranoit molybdenum - uranium - deposit of Oktyabr'skoe in Krasnokamensk described by VP Rogova, LN Belova, GN Kiziyarov and NN Koznetsova that the mineral based on its most important connection components in Russia and calcium notified and uranium .

classification

In the meanwhile outdated system of minerals according to Strunz (8th edition) , calciouranoite still belongs to the common division of "uranyl hydroxides and hydrates", where it forms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

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.) and predominantly UO 2 (O, OH) 5 pentagonal polyhedra” section, where it only together with bauranoite and metacalciouranoite forms the unnamed group 4.GB.2 .

The systematics of minerals according to Dana , which is common in the English-speaking world , also assigns the calciouranoite to the class of oxides, but there in the division of " uranium and thorium-containing oxides containing alkaline earth metal elements (hydrated) ", where it, together with bauranoite, is the unnamed Group 04/05/02 forms.

Crystal structure

Calciouranoite initially crystallizes triclinic with, however, previously unknown space group or unknown lattice parameters . Due to the ionizing radiation of the uranium contained in the chemical compound , however, the crystalline structure is destroyed over time and the calciouranoite metamictically amorphous .

properties

The mineral is very toxic due to the barium , lead and uranium components and, due to the latter element, is also highly radioactive with a specific activity of around 108 k Bq / g (for comparison: natural potassium 31.2 Bq / g).

Education and Locations

Calciouranoite forms deep in the oxidation zone of molybdenum-uranium deposits, in water-flooded, ore-bearing fault zones.

So far, in addition to its type locality Oktyabr'skoe near Krasnokamensk , the mineral could only be detected at two other sites (status: 2010): near Zadní Chodov in the Czech Republic and near Kyzyltyube-Sai in Tajikistan .

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

literature

Web links

Individual evidence

  1. ↑ a b c Webmineral - Calciouranoite (English).
  2. ↑ a b c d e Mindat - Calciouranoite .
  3. ^ 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.  251 .