Galaxite

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Galaxite
General
CategoryOxide minerals
Spinel group
Spinel structural group
Formula
(repeating unit)
(Mn,Fe2+,Mg)(Al,Fe3+)2O4
Strunz classification04.BB.05
Crystal symmetryIsometric (4/m 3 2/m) hexoctahedral
Unit cella = 8.271 Å; Z = 8
Identification
ColorBlack, red-brown, red to yellow
Crystal habitOctahedra and rounded grains and exolution blebs
Crystal systemCubic
TwinningSpinel law with {111} as both twin and composition plane
CleavageIndistinct to none
FractureConchoidal to irregular
TenacityBrittle
Mohs scale hardness7.5
LusterVitreous
StreakRed-brown
DiaphaneityOpaque; may be translucent in thin section
Specific gravity4.234
Optical propertiesIsotropic
Refractive indexn = 1.923
References[1][2][3]
 
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Galaxite
General
CategoryOxide minerals
Spinel group
Spinel structural group
Formula
(repeating unit)
(Mn,Fe2+,Mg)(Al,Fe3+)2O4
Strunz classification04.BB.05
Crystal symmetryIsometric (4/m 3 2/m) hexoctahedral
Unit cella = 8.271 Å; Z = 8
Identification
ColorBlack, red-brown, red to yellow
Crystal habitOctahedra and rounded grains and exolution blebs
Crystal systemCubic
TwinningSpinel law with {111} as both twin and composition plane
CleavageIndistinct to none
FractureConchoidal to irregular
TenacityBrittle
Mohs scale hardness7.5
LusterVitreous
StreakRed-brown
DiaphaneityOpaque; may be translucent in thin section
Specific gravity4.234
Optical propertiesIsotropic
Refractive indexn = 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]

References[edit]