{{Short description|Oxide mineral}} {{infobox mineral | name = Galaxite | category = Oxide minerals <br />Spinel group <br />Normal Spinel structural group | image = Galaxite-Jacobsite-Wiserite-697074.jpg | alt = | caption = Galaxite from the Kaso mine, Japan | formula = {{chem2|MnAl2O4}} | IMAsymbol = Glx<ref>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}</ref> | molweight = | strunz = 4.BB.05 | dana = | system = Cubic | class = Hexoctahedral (m{{overline|3}}m) <br/>H-M symbol: (4/m {{overline|3}} 2/m) | symmetry = ''Fd{{overline|3}}m'' (no. 227) | unit cell = a = 8.271 Å; Z = 8 | color = Black, red-brown, red to yellow | colour = | habit = Octahedra and rounded grains and exolution blebs | twinning = Spinel law with {111} as both twin and composition plane | cleavage = Indistinct to none | fracture = Conchoidal to irregular | tenacity = Brittle | mohs = 7.5 | luster = Vitreous | streak = Red-brown | diaphaneity = Opaque; may be translucent in thin section | gravity = 4.234 | density = | polish = | opticalprop = Isotropic | refractive = n = 1.923 | birefringence = | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = weakly to moderately magnetic | prop1 = | prop1text = | references = <ref name=Mindat>[http://www.mindat.org/min-1639.html Mindat.org ]</ref><ref name=HBM>[http://rruff.geo.arizona.edu/doclib/hom/galaxite.pdf Handbook of Mineralogy]</ref><ref name=Webmin>[http://webmineral.com/data/Galaxite.shtml Webmineral data]</ref> }} '''Galaxite''', also known as 'mangan-spinel' is an isometric mineral belonging to the spinel group of oxides with the ideal chemical formula {{chem2|Mn^{2+}Al2O4}}.<ref>{{Cite web|url=http://rruff.info/ima/|title = IMA Mineral List with Database of Mineral Properties}}</ref> It is sometimes used as a gemstone.<ref>Tables of Gemstone Identification By Roger Dedeyne, Ivo Quintens, p.282</ref>
==Occurrence== It was first described in 1932 for an occurrence at Bald Knob, Alleghany County, North Carolina near its namesakes, the town of Galax, Virginia, named after the plant galax or wandflower which grows in the area.<ref name=HBM/><ref name=Webmin/>
Galaxite generally occurs as small granular aggregates with a red-brownish tone. It has a vitreous luster and leaves a brownish-red streak. It is rated 7.5 on the Mohs Scale.<ref name=HBM/>
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.<ref name=HBM/>
==Composition== Galaxite is the manganese (Mn) rich endmember of the aluminium (Al) series of the spinel group. Divalent iron (Fe) and magnesium (Mg) readily substitute for the manganese in the crystal structure. Trivalent iron may also substitute for the aluminium. Thus, reflecting most natural samples, the formula may be better represented as {{chem2|(Mn,Fe^{2+},Mg)(Al,Fe^{3+})2O4}}.<ref name=HBM/>
==References== {{Reflist}} * [http://rruff.info/ima/ IMA Database - Galaxite]
Category:Manganese(II) minerals Category:Aluminium minerals Category:Oxide minerals Category:Spinel gemstones Category:Cubic minerals Category:Minerals in space group 227 Category:Minerals described in 1932
{{oxide-mineral-stub}}