Bixbyite

Bixbyite

Bixbyite from Utah
General
Category Oxide minerals
Formula
(repeating unit)		 (Mn,Fe)2O3
Strunz classification 04.CB.10
Dana classification 4.3.7.2
Crystal symmetry Isometric diploidal (2/m 3)
Unit cell a = 9.411 Å; Z = 16
Identification
Formula mass 158.33
Colour Black
Crystal habit Massive to crystalline
Crystal system Isometric
Twinning On {111}, as penetration twins
Cleavage Imperfect on {111}, in traces
Fracture Irregular to uneven
Mohs scale hardness 6 - 6½
Luster Metallic
Streak Black
Diaphaneity Opaque
Specific gravity 5.12
Density 4.95
Optical properties Isotropic
Common impurities Al, Mg, Si, Ti
References [1][2][3]

Bixbyite is a manganese iron oxide mineral with chemical formula: (Mn,Fe)2O3. The iron/manganese ratio is quite variable and many specimens have almost no iron. It is a metallic dark black with a Mohs hardness of 6.0 - 6.5.[1] It is a somewhat rare mineral sought after by collectors as it typically forms euhedral isometric crystals exhibiting various cubes, octahedra, and dodecahedra.

It is commonly associated with beryl, quartz, spessartine, hematite, pseudobrookite, hausmannite, braunite and topaz in pneumatolytic or hydrothermal veins and cavities and in metamorphic rocks. It can also be found in lithophysal cavities in rhyolite.[1] Typical localities are Jhabua and Chhindwara districts, India and the Thomas Range in Juab County, Utah. It is also reported from San Luis Potosi, Mexico; northern Patagonia, Argentina; Girona, Catalonia, Spain; Sweden and South Africa.[1]

Bixbyite was named for the American mineralogist Maynard Bixby (1853–1935), responsible for its discovery in 1897.[1] It should not be confused with bixbite, a red form of beryl; to avoid confusion, this name has been deprecated from the CIBJO.

See also

References

  1. 1 2 3 4 5 "Bixbyite mineral information and data". Mindat.org. Retrieved 24 January 2011.
  2. ↑ "Bixbyite Mineral Data". webmineral.com. Retrieved 24 January 2011.
  3. ↑ Handbook of Mineralogy

External links

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