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Category Oxide minerals
Spinel group
Spinel structural group
(repeating unit)
Strunz classification 04.BB.05
Crystal symmetry Isometric (4/m 3 2/m) hexoctahedral
Unit cell a = 8.271 Å; Z = 8
Color Black, red-brown, red to yellow
Crystal habit Octahedra and rounded grains and exolution blebs
Crystal system Cubic
Twinning Spinel law with {111} as both twin and composition plane
Cleavage Indistinct to none
Fracture Conchoidal to irregular
Tenacity Brittle
Mohs scale hardness 7.5
Luster Vitreous
Streak Red-brown
Diaphaneity Opaque; may be translucent in thin section
Specific gravity 4.234
Optical properties Isotropic
Refractive index n = 1.923
References [1][2][3]

Galaxite is a spinel mineral with the chemical formula (Mn,Fe2+,Mg)(Al,Fe3+)2O4.[2] It has a vitreous luster and is brownish red. It also leaves a brownish red streak. It is rated 7.5 on the Mohs Scale.[2]

It was first described in 1932 for an occurrence at Bald Knob, Alleghany County, North Carolina near its namesakes, the town of Galax, Virginia and the plant galax which grows in the area.[3][2]

It occurs in carbonate-rich metamorphosed manganese ore deposits. It occurs associated with alleghanyite, rhodonite, sonolite, spessartine, tephroite, kutnohorite, manganhumite, jacobsite, kellyite and alabandite in the Bald Knob area. Associated minerals include katoptrite, magnetite, manganostibite, magnussonite, tephroite, manganhumite and manganosite in the Brattfors mine area of Nordmark, Värmland, Sweden.[2]