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Single Modified Bixbyite Cube
OXIDES; SIMPLE OXIDES · ISOMETRIC

Bixbyite

(Mn,Fe)2O3

Hardness
5–6.5
Streak
Black
Spec. Gravity
4.9–5.1
System
Isometric

About

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.

Crystal Forms & 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.

Striking Features

Color, crystal habits, streak, and mode of occurrence

Environment

Uses

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.

Noteworthy Localities

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. 

Common Mineral Associations

Distinguishing Similar Minerals

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.

Photos

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Crystal forms

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Cubic With Modified Corners
Modified Cubic