Bystromite

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Bystromite
General and classification
chemical formula MgSb 2 O 6
Mineral class
(and possibly department) 		Oxides and hydroxides
System no. to Strunz
and to Dana 		4.DB.10 ( 8th edition : IV / D.04)
02.44.01.01
Crystallographic Data
Crystal system tetragonal
Crystal class ; symbol ditetragonal-dipyramidal; 4 / m 2 / m 2 / m
Room group (no.) P 4 2 / mnm (No. 136)
Lattice parameters a  = 4.68  Å ; c  = 9.21 Å
Formula units Z  = 2
Physical Properties
Mohs hardness ≈ 7
Density (g / cm 3 ) measured: 5.5 (1) to 5.7; calculated: 5.80
Cleavage Please complete!
colour blue-gray to yellowish brown
Line color light gray
transparency transparent to translucent
shine Please complete!
Crystal optics
Refractive index n  = 1.855 to 1.915
Optical character uniaxial

Byströmit is a very rare mineral from the mineral class of " oxides and hydroxides ". It crystallizes in the tetragonal crystal system with the composition MgSb 2 O 6 , so it is chemically a magnesium - antimony oxide.

Byströmit could only be found in the form of porous, massive mineral aggregates consisting of submicroscopic particles. Individual, microscopic crystals are transparent to translucent and have a blue-gray color, which can also deviate into yellowish brown due to the addition of stibiconite . The stroke color of Byströmit, however, is always light gray.

Etymology and history

Byströmit was first discovered in the "Mina la Fortuna" near El Antimoneo in the Municipio Caborca in the Mexican state of Sonora and described in 1952 by Brian Mason and Charles J. Vitaliano, who named the mineral after the crystal chemist Anders Byström (1916-1956), who named the Structure of the synthetic compound MgSb 2 O 6 analyzed.

Type material of the mineral was deposited in the Natural History Museum in London (register no. 1951,300) and in the National Museum of Natural History in Washington, DC (register no. 106194).

classification

In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the Byströmit belonged to the mineral class of "oxides and hydroxides" and there to the department of "oxides with the molar ratio of metal: oxygen = 1: 2", where it together with ordoñezite , Tapiolite (Fe) (formerly ferrotapiolite) and tapiolite (Mn) (formerly manganotapiolite) formed the "tapiolite group" IV / D.04 .

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns Byströmit to the class of "oxides and hydroxides" and there into the department of "oxides with the molar ratio of metal: oxygen = 1: 2 and comparable “. However, this section is further subdivided according to the relative size of the cations involved and the crystal structure, so that the mineral according to its composition and structure is classified in the sub-section “With medium-sized cations; Chains of edge-linked octahedra "can be found, where together with ferrotapiolite, manganotapiolite, ordoñezite the" tapiolite group "with the system no. 4.DB.10 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Byströmit, on the other hand, to the class of "phosphates, arsenates and vanadates" and there in the department of " antimonates ". Here it can be found together with ordoñezite and tripuhyite in the unnamed group 44.02.01 within the subdivision " Antimonates A (X 2 O 6 ) ".

Education and Locations

Byströmit forms in quartz - veins of weathered antimony deposits , where he primarily in paragenesis occurs with Stibiconit and quartz.

Apart from its type locality “Fortuna” mine in Mexico, the mineral has so far (as of 2012) only been found in the “Silver Rose” mine near Brandholz - Goldkronach in the Fichtelgebirge (Germany).

Crystal structure

Byströmit crystallizes tetragonally in the space group P 4 2 / mnm (space group no. 136) with the lattice parameters a  = 4.68  Å and c  = 9.21 Å as well as 2 formula units per unit cell .

See also

literature

Web links

Individual evidence

  1. ↑ Webmineral - Byströmite
  2. ↑ a b c d 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.  208 .
  3. ↑ a b c John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols: Byströmite , in: Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 68.3 kB )
  4. ↑ Mindat - Byströmite