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Single Modified Bixbyite Cube

The Mineral bixbyite

Bixbyite is an uncommon mineral, distinguished by its dark, lustrous crystals that are often exceptionally formed. The sharply formed crystals, combined with a frequently contrasting light rhyolite matrix, make this mineral very appealing to the collector.

Bixbyite is named in honor of Maynard Bixby (1853 – 1935) an American mineralogist, collector, and mineral dealer. Bixby explored the Thomas Range in Utah and staked several claims of Topaz, and he discovered Bixbyite there.
Chemical Formula (Mn,Fe)2O3
Composition Manganese iron oxide, sometimes with titanium
Variable Formula (Mn,Fe,Ti)2O3
Color Metallic black
Streak Black
Hardness 5 - 6.5
Crystal System Isometric
3D Crystal Atlas
(Click for animated model) 
Crystal Forms
and Aggregates
Crystals are cubic in shape, and they can be isolated or clustered together. Cubes usually have octahedral or dodecahedral modifications on the corners, which form in triangular formation. Crystals can also be in complex form with several square and triangular faces. Crystal edges and corners are usually deeply striated or etched. Crystals are usually small, rarely exceeding two centimeters. Also grainy and massive, especially in manganese ore localities.
Transparency Opaque
Specific Gravity 4.9 - 5.1
Luster Metallic
Cleavage 3,1
Fracture Uneven
Tenacity Brittle
In Group Oxides; Simple Oxides
Striking Features Color, crystal habits, streak, and mode of occurrence
Environment In rhyolite rocks and metamorphosed manganese deposits.
Rock Type Igneous, Metamorphic
Popularity (1-4) 3
Prevalence (1-3) 3
Demand (1-3) 1


Bixbyite is an important mineral for collectors due to its rarity and usual habit of well-formed crystals. Matrix specimens are especially desirable. Bixbyite is also a minor ore of manganese when mixed with other ores.

The premier locality for Bixbyite, which produces almost all collector specimens in sharp, lustrous crystals, is the Thomas Range, Juab Co., Utah. Small but well-formed crystals have also come from the Beryllium Virgin claim and the Taylor Creek Tin District, Sierra Co., New Mexico.

Dense crystal clusters of sharp cubic Bixbyite crystals have occurred in the N'Chwaning Mine, Kuruman, Kalahari Manganese Field, South Africa. Also in South Africa is the Postmasburg Manganese Field, Northern Cape Province. Micro crystals of Bixbite occur in the Eifel Mountains volcanic complex, Rhineland-Palatinate, Germany; and small crystals were found in Las Plumas, Chubut, Patagonia, Argentina. 

Topaz, Hematite, Beryl, Pseudobrookite, Manganite, Cassiterite, Hausmannite

The crystal habits, localities, color, streak, and high hardness are enough to distinguish Bixbyite from other minerals. The crude grainy and massive forms from manganese deposits are more difficult to distinguish from other manganese ores such as Braunite and Hausmannite.

bixbyite PHOTOS
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