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| formula = iron(II,III) manganese oxide, (Mn,Mg)Fe<sub>2</sub>O<sub>4</sub> |
| formula = iron(II,III) manganese oxide, (Mn,Mg)Fe<sub>2</sub>O<sub>4</sub> |
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| IMAsymbol = Jcb<ref>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols |
| IMAsymbol = Jcb<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> |
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| molweight = |
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| strunz = 4.BB.05 |
| strunz = 4.BB.05 |
Jacobsite | |
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General | |
Category | Oxide minerals Spinel group Spinel structural group |
Formula (repeating unit) | iron(II,III) manganese oxide, (Mn,Mg)Fe2O4 |
IMA symbol | Jcb[1] |
Strunz classification | 4.BB.05 |
Crystal system | Isometric |
Crystal class | Hexoctahedral (m3m) H-M symbol: (4/m 3 2/m) |
Space group | Fd3m |
Unit cell | a = 8.457 Å; Z = 8 |
Identification | |
Color | Black to brownish black |
Crystal habit | Disseminated to massive, rarely as octahedral crystals |
Twinning | Spinel law, flattened on {111} or lamellar |
Cleavage | {111}, probably a parting |
Fracture | Conchoidal |
Mohs scale hardness | 5.5 - 6.5 |
Luster | Metallic |
Streak | reddish black to brown |
Diaphaneity | Opaque |
Specific gravity | 4.76 |
Optical properties | Isotropic |
Refractive index | ~�2.3 |
Other characteristics | weakly magnetic |
References | [2][3] |
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.[2][4]
It occurs as a primary phase or as alteration of other manganese minerals during metamorphism of manganese deposits.[4] Typical associated minerals include hausmannite, galaxite, braunite, pyrolusite, coronadite, hematite and magnetite.[2] It is a ferrimagnetic substance, which is weakly attracted by a magnet.
It was first described in 1869 and named for the Jakobsberg Mine, Nordmark, Filipstad, Värmland, Sweden.[3]
This article about a specific oxide mineral is a stub. You can help Wikipedia by expanding it. |
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