Avicennit

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Avicennit
General and classification
chemical formula Tl 2 O 3
Mineral class
(and possibly department) 		Oxides and hydroxides
System no. to Strunz
and to Dana 		4.CB.10 ( 8th edition : IV / C.03)
03/04/08/01
Crystallographic Data
Crystal system cubic
Crystal class ; symbol m 3
Space group Ia 3 (No. 206)Template: room group / 206
Lattice parameters a  = 10.547  Å
Formula units Z  = 16
Physical Properties
Mohs hardness 1.5 to 2.5
Density (g / cm 3 ) measured: 8.9; calculated: 10.34
Cleavage Please complete!
Break ; Tenacity knitted to chopped up
colour grey black
Line color grey black
transparency opaque
shine metallic
Other properties
Chemical behavior soluble in acids

Avicennite is a very rare mineral from the mineral class of oxides and hydroxides . It crystallizes in the cubic crystal system with the chemical composition Tl 2 O 3 and is therefore chemically thallium (III) oxide . The mineral forms up to a millimeter in size, partly octahedral crystals as well as porous grains and coatings on carlinite of a gray-black color.

Etymology and history

The mineral was found in 1958 by KN Karpowa, EA Konkowa, ED Larkin and WF Saweljew near Dzhuzumli in Samarkand Province in what is now Uzbekistan . They named it after the Persian doctor Avicenna .

classification

In the old (8th edition) and new systematics of minerals according to Strunz (9th edition) , which is also used by the International Mineralogical Association (IMA), the Avicennit belongs to the department of “Oxides with the molar ratio metal  :  oxygen  = 2 : 3 “, whereby this department was expanded in the new Strunz'schen mineral systematics by the oxides with the molar ratio metal: oxygen = 3: 5 and comparable and also more precisely divided according to the size of the cations . Accordingly, the mineral is now in the sub-section “With medium-sized cations”. In both systems it forms a group with Bixbyit .

The systematics of minerals according to Dana also assigns the Avicennit to the class of oxides, but there in the division of "Simple oxides with a cation charge of 3+ and the general formula A 2 O 3 ", where it forms its own subgroup.

Education and Locations

Avicennit is formed either by oxidation of carlinite or by weathering in a hematite - calcite vein in silicified limestone . Depending on where it was found, it is associated with carlinite, hematite, quartz or parapierrotite .

Avicennit is very rare, only six sites are known so far. In addition to the type locality , the mineral was also found in He County in the Chinese province of Anhui and in Tibet in Lhorong County , Elko in the US state of Nevada , and in Tooele County in the US state of Utah . There is also a known site in Greece .

Crystal structure

Avicennite crystallizes in the cubic crystal system in the space group Ia 3 (space group number 206) with the lattice parameter a  = 10.547  Å and 16 formula units per unit cell . Template: room group / 206

Precautions

Avicennite is one of the most toxic minerals due to its high thallium content , so great care should be taken when handling it.

See also

literature

  • HH Otto, R. Baltrusch, H.-J. Brandt: Further evidence for Tl 3+ in Tl-based superconductors from improved bond strength parameters involving new structural data of cubic Tl 2 O 3 , 1993, Materialwissenschaftliche Kristallographie, TU Clausthal, doi : 10.1016 / 0921-4534 (93) 90382-Z

Web links

Individual evidence

  1. ↑ a b c Avicennite. , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 68 kB , English)
  2. ↑ a b Mineralienatlas: Avicennit
  3. ↑ New Dana Classification of Oxide Minerals (English)
  4. ↑ Mindat - Avicennite (English)