View source for Gahnite

{{Infobox mineral
| name        = Gahnite
| category    = [[Oxide minerals]] <br />[[Spinel group]] <br />Spinel structural group
| boxwidth    =
| image       = Gahnite.jpg
| imagesize   = 260px
| caption     =
| formula     = ZnAl<sub>2</sub>O<sub>4</sub>
| IMAsymbol   = Ghn<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>
| strunz      = 4.BB.05
| system      = [[Isometric crystal system|Cubic]]
| class       = Hexoctahedral (m{{overline|3}}m) <br/>[[H-M symbol]]: (4/m {{overline|3}} 2/m)
| symmetry    = ''Fd''{{overline|3}}m
| color       = Dark green, bluish green, blue to indigo, yellow to brown
| habit       = Typically octahedra, rarely as dodecahedra also massive to granular
| twinning    = Common on [111] produces striations
| cleavage    = Indistinct parting on [111]
| fracture    = Conchoidal, uneven
| mohs        = 7.5–8.0
| luster      = Vitreous
| refractive  = n = 1.79–1.80
| opticalprop = Isotropic
| birefringence =
| pleochroism =
| streak      = Grey
| gravity     = 4.38–4.60
| melt        =
| fusibility  =
| diagnostic  =
| solubility  =
| diaphaneity = Translucent to nearly opaque
| other       =
| references  = <ref name=Handbook>{{cite web |last1=Anthony |first1=John W. |last2=Bideaux |first2=Richard A. |last3=Bladh |first3=Kenneth W. |last4=Nichols |first4=Monte C. |title=Gahnite |url=http://www.handbookofmineralogy.org/pdfs/gahnite.pdf |website=Handbook of Mineralogy |publisher=Mineral Data Publishing |access-date=14 March 2022 |date=2005}}</ref><ref name=Mindat>{{mindat|id=1632|title=Gahnite}}</ref><ref name=Webmineral>http://webmineral.com/data/Gahnite.shtml Webmineral</ref>
}}
'''Gahnite''', ZnAl<sub>2</sub>O<sub>4</sub>, is a rare mineral belonging to the [[spinel]] group. It forms octahedral crystals which may be green, blue, yellow, brown or grey. It often forms as an alteration product of [[sphalerite]] in altered massive sulphide deposits such as at [[Broken Hill]], Australia. Other occurrences include [[Falun]], [[Sweden]] where it is found in [[pegmatites]] and [[skarn]]s; and, in the [[United States]], [[Charlemont, Massachusetts]]; [[Spruce Pine, North Carolina]]; [[White Picacho district, Arizona]]; [[Topsham, Maine]]; and [[Franklin, New Jersey]].<ref name=Handbook/><ref name=Mindat/>
It was first described in 1807 for an occurrence in the Falu mine, Falun, Dalarna, Sweden, and named after the Swedish chemist, [[Johan Gottlieb Gahn]] (1745–1818), the discoverer of the element [[manganese]].<ref name=Mindat/><ref name=Webmineral/> It is sometimes called ''zinc spinel''.
==See also==
* [[List of minerals named after people]]
==References==
{{Reflist}}
{{Commons category}}
[[Category:Zinc minerals]]
[[Category:Aluminium minerals]]
[[Category:Spinel group]]
[[Category:Cubic minerals]]
[[Category:Minerals in space group 227]]
[[Category:Minerals described in 1807]]
{{Oxide-mineral-stub}}