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.
Spinel Group, Al series. Gahnite-Hercynite Series, and the Gahnite-Spinel Series.
Visit gemdat.org for gemological information about Gahnite.
Visit gemdat.org for gemological information about Gahnite.
Classification of Gahnite
Approved, 'Grandfathered' (first described prior to 1959)
4/B.01-40
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
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 : MULTIPLE OXIDES
2 : AB2X4
7.5.5
7 : Oxides and Hydroxides
5 : Oxides of Zn, Cd and Hg
7 : Oxides and Hydroxides
5 : Oxides of Zn, Cd and Hg
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)
Optical Data of Gahnite
Type:
Isotropic
Chemical Properties of Gahnite
Formula:
ZnAl2O4
Elements listed in formula:
Common Impurities:
Fe,Mg
Crystallography of Gahnite
Crystal System:
Isometric
Class (H-M):
m3m (4/m 3 2/m) - Hexoctahedral
Space Group:
Fd3m
Cell Parameters:
a = 8.062 Å
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 courtesy of RRUFF project at University of Arizona, used with permission.
Type Occurrence of Gahnite
Relationship of Gahnite to other Species
Member of:
Other Members of Group:
| Chromite | Fe2+Cr23+O4 |
| Cochromite | (Co,Ni,Fe)(Cr,Al)2O4 |
| Coulsonite | Fe2+V23+O4 |
| Cuprospinel | Cu2+Fe23+O4 |
| Filipstadite | (Sb0.5Fe0.5)Mn2O4 |
| Franklinite | Zn2+Fe23+O4 |
| Galaxite | Mn2+Al2O4 |
| Hercynite | Fe2+Al2O4 |
| Jacobsite | Mn2+Fe23+O4 |
| Magnesiochromite | MgCr2O4 |
| Magnesiocoulsonite | MgV2O4 |
| Magnesioferrite | MgFe23+O4 |
| Magnetite | Fe2+Fe23+O4 |
| Manganochromite | Mn2+Cr2O4 |
| Nichromite | (Ni,Co,Fe)(Cr,Fe,Al)2O4 |
| Qandilite | (Mg,Fe3+)2(Ti,Fe3+,Al)O4 |
| Spinel | MgAl2O4 |
| Trevorite | Ni2+Fe23+O4 |
| Ulvöspinel | Fe2TiO4 |
| Vuorelainenite | Mn2+V23+O4 |
| Xieite | Fe2+Cr2O4 |
| Zincochromite | ZnCr2O4 |
| 4.BB.05 | Chromite | Fe2+Cr2O4 |
| 4.BB.05 | Cochromite | CoCr2O4 |
| 4.BB.05 | Coulsonite | Fe2+V23+O4 |
| 4.BB.05 | Cuprospinel | Cu2+Fe23+O4 |
| 4.BB.05 | Filipstadite | (Mn2+,Mg)2(Sb5+,Fe3+)O4 |
| 4.BB.05 | Franklinite | ZnFe23+O4 |
| 4.BB.05 | Galaxite | Mn2+Al2O4 |
| 4.BB.05 | Hercynite | Fe2+Al2O4 |
| 4.BB.05 | Jacobsite | Mn2+Fe23+O4 |
| 4.BB.05 | Manganochromite | Mn2+Cr2O4 |
| 4.BB.05 | Magnesiocoulsonite | MgV2O4 |
| 4.BB.05 | Magnesiochromite | MgCr23+O4 |
| 4.BB.05 | Magnesioferrite | MgFe23+O4 |
| 4.BB.05 | Magnetite | Fe2+Fe23+O4 |
| 4.BB.05 | Nichromite | (Ni,Co,Fe)(Cr,Fe,Al)2O4 |
| 4.BB.05 | Qandilite | Mg2(Ti,Fe3+,Al)O4 |
| 4.BB.05 | Spinel | MgAl2O4 |
| 4.BB.05 | Trevorite | NiFe23+O4 |
| 4.BB.05 | Ulvöspinel | Fe22+TiO4 |
| 4.BB.05 | Vuorelainenite | Mn2+V23+O4 |
| 4.BB.05 | Zincochromite | ZnCr2O4 |
| 4.BB.10 | Hausmannite | Mn2+Mn23+O4 |
| 4.BB.10 | Hetaerolite | ZnMn23+O4 |
| 4.BB.10 | Hydrohetaerolite | HZnMn3+5/3O4 |
| 4.BB.10 | Iwakiite | Mn2+Fe23+O4 |
| 4.BB.15 | Maghemite | Fe2.67O4 |
| 4.BB.15 | Titanomaghemite | Fe(Fe,Ti)2O4 |
| 4.BB.20 | Tegengrenite | Mg2(Sb,Mn)O4 |
| 4.BB.25 | Xieite | FeCr2O4 |
| 7.5.1 | Zincite | ZnO |
| 7.5.2 | Sweetite | Zn(OH)2 |
| 7.5.3 | Ashoverite | Zn(OH)2 |
| 7.5.4 | Wülfingite | Zn(OH)2 |
| 7.5.6 | Hetaerolite | ZnMn23+O4 |
| 7.5.7 | Hydrohetaerolite | HZnMn3+5/3O4 |
| 7.5.8 | Chalcophanite | ZnMn34+O7 · 3H2O |
| 7.5.9 | Woodruffite | Zn2Mn54+O12 · 4H2O |
| 7.5.10 | Franklinite | ZnFe23+O4 |
| 7.5.11 | Monteponite | CdO |
| 7.5.12 | Montroydite | HgO |
Other Names for Gahnite
Name in Other Languages:
French:Spinelle Zincifère
Italian:Gahnite
Portuguese:Gahnita
Russian:Ганит
Spanish:Automalita
Automolita
Gahnita
Automolita
Gahnita
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.
Adriana Heimann, Jason A. Yonts, and Miguel A. Galliski (2015): The Composition of Gahnite In Granitic Pegmatites From the Pampean Pegmatite Province, Argentina: Implications For Pegmatite Fractionation. Can. Mineral. 53, 991-1014.
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.
Adriana Heimann, Jason A. Yonts, and Miguel A. Galliski (2015): The Composition of Gahnite In Granitic Pegmatites From the Pampean Pegmatite Province, Argentina: Implications For Pegmatite Fractionation. Can. Mineral. 53, 991-1014.
Internet Links for Gahnite
mindat.org URL:
https://www.mindat.org/min-1632.html
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Please feel free to link to this page.
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Specimens:
The following Gahnite specimens are currently listed for sale on minfind.com.
Franklin Mine, Franklin, Franklin Mining District, Sussex Co., New Jersey, USA