Bixbyite - Encyclopedia

    Class : Oxides and hydroxides
    Subclass : Oxides
    Crystal system : Cubic
    Chemistry : (Mn,Fe)2O3
    Rarity : Uncommon to rare


Bixbyite forms a solid solution with the term Mn2O3. It is a fairly rare mineral that is found in two types of environments : metamorphic manganese deposits, "gondites", and rhyolite lithophyses. It owes its name to the American mineralogist and mineral merchant Maynard Bixby. Bixbyite most commonly forms shiny black masses, as well as small cubic and cubo-octahedral crystals with shiny faces. Under the metallographic microscope, it is characterized by the constant presence of polysynthetic twins organized in square patterns. It is a mineral little known to collectors and which constitutes an accessory ore of manganese.

Bixbyite in the World

Bixbyite is common in manganese deposits in the districts of Postmasburg and Kuruman (South Africa) and Sitapar (India), as well as in Langban (Sweden), where it is mined along with other manganese minerals. It is generally massive there, sometimes in superb crystals measuring up to 10 mm (Lohatlha). But the most beautiful crystals of bixbyite are found in the lithophyses of hydrothermalized rhyolites. In the Thomas Range Mountains (Utah), bixbyite forms magnificent cubes exceeding 15 mm (main photo) sometimes deposited on crystals of honey yellow topaz. Similar associations are known in the neighboring locality of the Wah Wah Mountains as well as in Mexico (San Luis Potosi).

Bixbyite in France

In France, bixbyite is reported in Saphoz (Haute-Saône), Gérardmer (Vosges) as well as Maljasset (Alpes-de-Hautes-Provence).

Twinning

The bixbyte commonly twins on {111}. This multiple twin creates crenellated edges (main photo).

The different crystal forms of bixbyite

All the crystalline forms presented below have a printable and assemblable pattern, see section "our crystallographic models".

Bixbyite - Perfect cube

Bixbyite cube truncated by faces 112, 121, 211 and following

Bixbyite cube with development of faces 112, 121, 211 and following

Bixbyite - Overdevelopment of faces 112, 121, 211 and following (rare)

Fakes and scams

No scam known for this mineral.



Hardness : 6 to 6.5
Density : 4.945
Fracture : Irregular
Trace : Black



TP : Opaque
RI : -
Birefringence : None
Optical character : None
Pleochroism : None
Fluorescence : None


Solubility : Hydrochloric acid
Magnetism : None
Radioactivity : None

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