Galaxite, also known as 'mangan-spinel' is an isometric

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...

belonging to the

spinel group The spinels are any of a class of minerals of general formulation which crystallise in the cubic (isometric) crystal system, with the X anions (typically chalcogens, like oxygen and sulfur) arranged in a cubic close-packed lattice and the cation ...

of oxides with the ideal

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbol ...

. Galaxite is the

manganese Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...

(Mn) rich endmember of the

aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...

(Al) series of the

Divalent In chemistry, the valence (US spelling) or valency (British spelling) of an chemical element, element is the measure of its combining capacity with other atoms when it forms chemical compounds or molecules. Description The combining capacity, ...

iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundanc ...

(Fe) and

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...

(Mg) readily substitute for the manganese in the crystal structure.

Trivalent In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with other atoms when it forms chemical compounds or molecules. Description The combining capacity, or affinity of an ...

iron may also substitute for the aluminium. Thus, reflecting most natural samples, the formula may be better represented as . 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 The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by th ...

. 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 Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclu ...

galax ''Galax'', the wandplant, wandflower, or beetleweed, is a genus in the flowering plant family Diapensiaceae, containing a single species, ''Galax urceolata'' ( syn. ''G. rotundifolia'', ''G. aphylla''). It is native to the southeastern United S ...

or wandflower which grows in the area. It occurs in carbonate-rich

metamorphosed Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causi ...

ore deposits. It occurs associated with

alleghanyite Alleghanyite is a moderately rare humite mineral with formula Mn5(SiO4)2(OH)2, belonging to the nesosilicates class. In general its occurrences are related with metamorphic (metamorphosed) manganese deposits. The mineral is named after Alleghany ...

rhodonite Rhodonite is a manganese inosilicate, (Mn, Fe, Mg, Ca)SiO3 and member of the pyroxenoid group of minerals, crystallizing in the triclinic system. It commonly occurs as cleavable to compact masses with a rose-red color (the name comes from the G ...

sonolite Sonolite is a mineral with formula Mn9(SiO4)4(OH,F)2. The mineral was discovered in 1960 in the Sono mine in Kyoto Prefecture, Japan. In 1963, it was identified as a new mineral and named after the Sono mine. Description Sonolite is transparent ...

spessartine Spessartine is a nesosilicate, manganese aluminium garnet species, Mn2+3Al2(SiO4)3.Gemological Institute of America, ''GIA Gem Reference Guide'' 1995, This mineral is sometimes mistakenly referred to as ''spessartite''. Spessartine's name is a ...

tephroite Tephroite is the manganese endmember of the olivine group of nesosilicate minerals with the formula Mn2 Si O4. A solid solution series exists between tephroite and its analogues, the group endmembers fayalite and forsterite. Divalent iron or m ...

kutnohorite Kutnohorite is a rare calcium manganese carbonate mineral with magnesium and iron that is a member of the dolomite group. It forms a series with dolomite, and with ankerite. The end member formula is , but and commonly substitute for , with ...

, manganhumite,

jacobsite Jacobsite is a manganese iron oxide mineral. It is in the spinel group and forms a solid solution series with magnetite. The chemical formula is (Mn,Mg)Fe2O4 or with oxidation states and substitutions: (Mn2+,Fe2+,Mg)(Fe3+,Mn3+)2O4.

, kellyite and

alabandite Alabandite or alabandine is a rarely occurring manganese sulfide mineral. It crystallizes in the cubic crystal system with the chemical composition Mn2+ S and develops commonly massive to granular aggregates, but rarely also cubic or octahedral ...

in the Bald Knob area. Associated minerals include katoptrite,

magnetite Magnetite is a mineral and one of the main iron ores, with the chemical formula Fe2+Fe3+2O4. It is one of the oxides of iron, and is ferrimagnetic; it is attracted to a magnet and can be magnetized to become a permanent magnet itself. With th ...

, manganostibite, magnussonite,

, manganhumite and

manganosite Manganosite is a rare mineral composed of manganese(II) oxide MnO. It was first described in 1817 for an occurrence in the Harz Mountains, Saxony-Anhalt, Germany. It has also been reported from Langban and Nordmark, Sweden and at Franklin Furna ...

in the Brattfors mine area of

Nordmark The Northern March or North March (german: Nordmark) was created out of the division of the vast ''Marca Geronis'' in 965. It initially comprised the northern third of the ''Marca'' (roughly corresponding to the modern state of Brandenburg) and ...

Värmland Värmland () also known as Wermeland, is a '' landskap'' (historical province) in west-central Sweden. It borders Västergötland, Dalsland, Dalarna, Västmanland, and Närke, and is bounded by Norway in the west. Latin name versions are '' ...

, Sweden. It is sometimes used as a gemstone.Tables of Gemstone Identification By Roger Dedeyne, Ivo Quintens, p.282

References

IMA Database - Galaxite
Manganese(II) minerals Iron(II,III) minerals Magnesium minerals Aluminium minerals Spinel gemstones Cubic minerals Minerals in space group 227 Oxide minerals {{oxide-mineral-stub