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Gahnite

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Johan Gottlieb Gahn
Formula:
ZnAl2O4
System:
Isometric
Colour:
Dark blue-green, yellow, ...
Lustre:
Vitreous
Hardness:
7½ - 8
Member of:
Name:
Named in 1807 by Baron Karl Marie Ehrenbert von Moll in honor of Swedish chemist and mineralogist, Johan Gottlieb Gahn [August 19, 1745 Voxna Bruk, Hälsingland, Sweden - December 8, 1818 Falun, Sweden]. The new name replaced automalite named by Anders Gustav Ekeberg.

Classification of Gahnite

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
4.BB.05

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
B : Metal: Oxygen = 3:4 and similar
B : With only medium-sized cations
7.2.1.4

7 : MULTIPLE OXIDES
2 : AB2X4
7.5.5

7 : Oxides and Hydroxides
5 : Oxides of Zn, Cd and Hg
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First Recorded Occurrence of Gahnite

Year of Discovery:
1807

Physical Properties of Gahnite

Vitreous
Colour:
Dark blue-green, yellow, brown, black
Streak:
Grey
Hardness (Mohs):
7½ - 8
Tenacity:
Brittle
Fracture:
Irregular/Uneven, Conchoidal
Density:
4.62 g/cm3 (Calculated)

Crystallography of Gahnite

Crystal System:
Isometric
Class (H-M):
m3m (4/m 3 2/m) - Hexoctahedral
Space Group:
Fd3m
Cell Parameters:
a = 8.062Å
Unit Cell Volume:
V 524.00 ų (Calculated from Unit Cell)
Morphology:
Crystals usually octahedral.
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Optical Data of Gahnite

Type:
Isotropic

Chemical Properties of Gahnite

Formula:
ZnAl2O4
Essential elements:
All elements listed in formula:
Common Impurities:
Fe,Mg

Relationship of Gahnite to other Species

Series:
Forms a series with Spinel (see here)
Forms a series with Hercynite (see here)
Member of:
Other Members of Group:
Ceylonite
ChromiteFe2+Cr23+O4
Cochromite(Co,Ni,Fe)(Cr,Al)2O4
CoulsoniteFe2+V23+O4
CuprospinelCu2+Fe23+O4
Filipstadite(Sb0.5Fe0.5)Mn2O4
FrankliniteZn2+Fe23+O4
Galaxite(Mn,Fe,Mg)(Al,Fe)2O4
HercyniteFe2+Al2O4
JacobsiteMn2+Fe23+O4
MagnesiochromiteMg(Cr,Al,Fe)2O4
MagnesiocoulsoniteMgV2O4
MagnesioferriteMgFe23+O4
MagnetiteFe2+Fe23+O4
Manganochromite(Mn,Fe)(Cr,V)2O4
Nichromite(Ni,Co,Fe)(Cr,Fe,Al)2O4
Qandilite(Mg,Fe)2(Ti,Fe,Al)O4
SpinelMgAl2O4
TrevoriteNi2+Fe23+O4
UlvöspinelFe2TiO4
Vuorelainenite(Mn,Fe)(V,Cr)2O4
ZincochromiteZnCr2O4
4.BB.05ChromiteFe2+Cr23+O4
4.BB.05Cochromite(Co,Ni,Fe)(Cr,Al)2O4
4.BB.05CoulsoniteFe2+V23+O4
4.BB.05CuprospinelCu2+Fe23+O4
4.BB.05Filipstadite(Sb0.5Fe0.5)Mn2O4
4.BB.05FrankliniteZn2+Fe23+O4
4.BB.05Galaxite(Mn,Fe,Mg)(Al,Fe)2O4
4.BB.05HercyniteFe2+Al2O4
4.BB.05JacobsiteMn2+Fe23+O4
4.BB.05Manganochromite(Mn,Fe)(Cr,V)2O4
4.BB.05MagnesiocoulsoniteMgV2O4
4.BB.05MagnesiochromiteMg(Cr,Al,Fe)2O4
4.BB.05MagnesioferriteMgFe23+O4
4.BB.05MagnetiteFe2+Fe23+O4
4.BB.05Nichromite(Ni,Co,Fe)(Cr,Fe,Al)2O4
4.BB.05Qandilite(Mg,Fe)2(Ti,Fe,Al)O4
4.BB.05SpinelMgAl2O4
4.BB.05TrevoriteNi2+Fe23+O4
4.BB.05UlvöspinelFe2TiO4
4.BB.05Vuorelainenite(Mn,Fe)(V,Cr)2O4
4.BB.05ZincochromiteZnCr2O4
4.BB.10HausmanniteMn2+Mn23+O4
4.BB.10HetaeroliteZnMn2O4
4.BB.10HydrohetaeroliteZnMn2O4 · H2O
4.BB.10IwakiiteMn2+Fe23+O4
4.BB.15MaghemiteFe23+O3
4.BB.15TitanomaghemiteFe3+(Fe3+,Ti4+,Fe2+,◻)2O4
4.BB.20Tegengrenite(Mg,Mn2+)2Sb5+0.5(Mn3+,Si,Ti)0.5O4
4.BB.25XieiteFe2+Cr2O4
7.5.1Zincite(Zn,Mn2+,Fe2+)O
7.5.2SweetiteZn(OH)2
7.5.3AshoveriteZn(OH)2
7.5.4WülfingiteZn(OH)2
7.5.6HetaeroliteZnMn2O4
7.5.7HydrohetaeroliteZnMn2O4 · H2O
7.5.8Chalcophanite(Zn,Fe,Mn)Mn3O7 · 3H2O
7.5.9WoodruffiteZn(Mn4+,Mn3+)5O10·3½H2O
7.5.10FrankliniteZn2+Fe23+O4
7.5.11MonteponiteCdO
7.5.12MontroyditeHgO

Other Names for Gahnite

Name in Other Languages:

Other Information

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Gahnite

Reference List:
Palache, Charles, Harry Berman & Clifford Frondel (1944), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Seventh edition, Volume I: 689-697.

Mineralogical Magazine: 62: 41-54.

Spry, P.G. (1987) Compositional zoning in zincian spinel. Canadian Mineralogist: 25: 97-104.

Waerenborgh, J.C., Annersten, H., Ericsson, T., Figueiredo, M.O., and Cabral, J.M.P. (1990) A Mössbauer study of natural gahnite spinels showing strongly temperature dependent quadrupole splitting distributions. European Journal of Mineralogy: 2: 267-271.

O'Neill, H.St.C. and Dollase, W.A. (1994) Crystal structures and cation distribution in simple spinels from powder XRD structural refinements: MgCr2O4, ZnCr2O4, Fe3O4, and the temperature dependence of the cation distribution in ZnAl2O4. Physics and Chemistry of Minerals: 20: 541-555.

Hålenius, U. and Bosi, F (2014) Color of Mn-bearing gahnite: A first example of electronic transitions in heterovalent exchange coupled IVMn2+ - VIMn3+ pairs in minerals. American Mineralogist 99, 261-266.

Internet Links for Gahnite

Specimens:
The following Gahnite specimens are currently listed for sale on minfind.com.

Localities for Gahnite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
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