Oxide minerals <br />Spinel group <br />Spinel structural group
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Infobox - added "weakly magnetic"
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| solubility = |
| solubility = |
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| diaphaneity = Opaque |
| diaphaneity = Opaque |
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| other = |
| other = weakly magnetic |
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| references = <ref name=Handbook>[http://rruff.geo.arizona.edu/doclib/hom/jacobsite.pdf Handbook of Mineralogy]</ref><ref name=Mindat>[http://www.mindat.org/min-2061.html Mindat.org]</ref> |
| references = <ref name=Handbook>[http://rruff.geo.arizona.edu/doclib/hom/jacobsite.pdf Handbook of Mineralogy]</ref><ref name=Mindat>[http://www.mindat.org/min-2061.html Mindat.org]</ref> |
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Jacobsite | |
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General | |
Category | Oxide minerals Spinel group Spinel structural group |
Formula (repeating unit) | iron(II,III) manganese oxide, MnFe2O4 |
Strunz classification | 04.BB.05 |
Crystal system | Isometric Hexoctahedral |
Space group | Isometric (4/m 3 2/m) |
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 | [1][2] |
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 MnFe2O4 or with oxidation states and substitutions: (Mn2+,Fe2+,Mg)(Fe3+,Mn3+)2O4.[1][3]
It occurs as a primary phase or as alteration of other manganese minerals during metamorphism of manganese deposits.[3] Typical associated minerals include hausmannite, galaxite, braunite, pyrolusite, coronadite, hematite and magnetite.[1]
It was first described in 1869 and named for the Jakobsberg Mine, Nordmark, Filipstad, Värmland, Sweden.[2]
This article about a specific oxide mineral is a stub. You can help Wikipedia by expanding it. |
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Borates |
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Carbonates |
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Oxides |
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Phosphates |
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Silicates |
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Sulfides |
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Other |
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