Galaxite

Galaxite
General
Category	Oxide minerals - Spinel
Chemical formula	(Mn,Fe,Mg)(Al,Fe)2O4
Strunz classification	04.BB.05
Crystal symmetry	Isometric (4/m 3 2/m) hexoctahedral
Unit cell	a = 8.271 Å; Z = 8
Identification
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

Galaxite is a spinel mineral with the chemical formula (Mn,Fe,Mg)(Al,Fe)₂O₄. 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.

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.

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 of katoptrite, magnetite, manganostibite, magnussonite, tephroite, manganhumite and manganosite in the Brattfors mine area of Nordmark, Värmland, Sweden.