Bixbyite

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Bixbyite
Bixbyite-160214.jpg
Bixbyite specimen from the "N'Chwaning I Mine" near Kuruman , Kalahari, South Africa (size: 3.9 cm × 2.9 cm × 2.4 cm)
General and classification
other names
chemical formula Mn 3+ 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)
03/04/07/02
Crystallographic Data
Crystal system cubic
Crystal class ; symbol cubic-disdodecahedral; 2 / m 3
Room group (no.) Ia 3 (No. 206)
Lattice parameters a  = 9.41  Å
Formula units Z  = 16
Twinning Penetration twins according to {111}
Physical Properties
Mohs hardness 6 to 6.5
Density (g / cm 3 ) measured: 4.945; calculated: 5.031
Cleavage indistinct after {111}
Break ; Tenacity shell-like to uneven
colour black
Line color black
transparency opaque
shine Metallic luster

Bixbyite , not to be confused with the outdated trade name Bixbit for red beryl , is a rarely occurring mineral from the mineral class of " oxides and hydroxides ". It crystallizes in the cubic crystal system with the idealized composition Mn 3+ 2 O 3 , so chemically speaking it is manganese (III) oxide . Since naturally formed bixbyite is always found with a small amount of iron , which replaces the manganese , the formula is often also given as (Mn, Fe) 2 O 3 .

Bixbyite is opaque and usually develops black, cubic crystals and combinations as well as crystal twins up to about six centimeters in size, the surfaces of which have a metallic sheen .

Etymology and history

The mineral was named after the American prospector , mineral dealer, author and researcher of the Thomas Mountains Maynard Bixby (1853-1935), who collected and delivered the first specimens.

Bixbyite was found for the first time in 1897 in "Maynard's Claim" ( Pismire Knolls ) in Juab County (Utah) and described by Samuel Lewis Penfield (1856-1906) and HW Foote.

classification

In the now obsolete, but still common 8th edition of the mineral classification by Strunz the Bixbyit belong to the department of "oxides having the mole ratio of metal: oxygen = 2: 3 (M 2 O 3 and related compounds)" where he together with avicennite the "Bixbyit series" with the system no. IV / C.03 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 Bixbyit to the expanded section of "Oxides with a metal: oxygen ratio of 2: 3, 3: 5 and comparable". This is also more precisely subdivided according to the relative size of the cations involved , so that the mineral can be found according to its composition in the sub-section "With medium-sized cations", where it is also together with Avicennit the "Bixbyit group" with the system no. 4.CB.10 forms.

The systematics of minerals according to Dana also assigns bixbyite to the class of "oxides and hydroxides" and there in the department of "oxides". Here it can be found together with Maghemite in the unnamed group 04.03.07 within the subsection “Simple oxides with a cation charge of 3+ (A 2 O 3 )”.

Education and Locations

Crystal specimen with bixbyite and topaz (size: 2.6 cm × 1.7 cm × 1.1 cm) from Thomas Range, Juab County, Utah, USA
Perfectly developed disdodecahedral bixbyite from the Wah Wah Mountains (Beaver County), Utah, USA (image size: 4.1 mm × 5.3 mm)

Bixbyite is formed either through hydrothermal processes in rhyolite chambers or in metamorphic manganese ore deposits . Accompanying minerals include beryl , braunite , hematite , pseudobrookite , quartz , sanidine , spessartine and topaz .

Bixbyite has so far (as of 2010) been found at around 80 sites worldwide. In Germany the mineral was found near Fahlenbach and in the "Ferdinand Mine" near Unterkirnach (Baden-Württemberg) as well as in several places in the Eifel (Rhineland-Palatinate). In Austria, Bixbyit has so far performed in the Goldzechscharte am Hocharn (Carinthia) and the Goldzechkopf ( Goldberg group , Salzburg).

Other locations are Afghanistan , Argentina , Australia , Bolivia , China , France , India , Italy , Japan , Mexico , Namibia , Sweden , Zimbabwe , Spain , South Africa , Tanzania , Turkey , the United Kingdom (Great Britain) and the United States of America (UNITED STATES).

Crystal structure

Bixbyite crystallizes cubically in the space group Ia 3 (space group number 206) with the lattice parameter a  = 9.41  Å and 16 formula units per unit cell .

See also

literature

Web links

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

Individual evidence

  1. ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 5th completely revised and supplemented edition. Weise, Munich 2008, ISBN 978-3-921656-70-9 .
  2. ↑ Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 , p.  409 .
  3. ↑ a b IMA / CNMNC List of Mineral Names; February 2013 (PDF 1.3 MB)
  4. ↑ a b Bixbyite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 68.4 kB )
  5. ↑ 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.  194 .
  6. ^ Archive.org - Felix Dietrich, Reinhard Dietrich: Bibliography of German magazine literature (1898)
  7. ↑ Mindat - Localities for Bixbyite