# Jacobsite

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> Markdown URL: https://mediated.wiki/source/Jacobsite.md
> Source: https://en.wikipedia.org/wiki/Jacobsite
> Source revision: 1336710435
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

{{Short description|Manganese iron oxide mineral}}
{{Infobox mineral
| name        = Jacobsite
| category    = [Oxide minerals](/source/Oxide_minerals) <br />[Spinel group](/source/Spinel_group) <br />Spinel structural group
| boxwidth    = 
| image       = Jacobsite-cktsr-15a.jpg
| imagesize   = 260px
| caption     = 
| formula     = iron(II,III) manganese oxide, (Mn,Mg)Fe<sub>2</sub>O<sub>4</sub>
| 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>
| molweight   = 
| strunz      = 4.BB.05
| system      = [Isometric](/source/Cubic_crystal_system)
| class       = Hexoctahedral (m{{overline|3}}m) <br/>[H-M symbol](/source/H-M_symbol): (4/m {{overline|3}} 2/m)
| symmetry    = ''Fd{{overline|3}}m'' (no. 227)
| unit cell   = a = 8.457&nbsp;Å; Z&nbsp;=&nbsp;8
| color       = Black to brownish black
| habit       = Disseminated to massive, rarely as octahedral crystals
| twinning    = Spinel law, flattened on {111} or lamellar
| cleavage    = {111}, probably a parting
| fracture    = Conchoidal
| mohs        = 5.5–6.5
| luster      = Metallic
| refractive  = ~2.3
| opticalprop = Isotropic
| birefringence = 
| pleochroism = 
| streak      = reddish black to brown
| gravity     = 4.76
| density     = 
| melt        = 
| fusibility  = 
| diagnostic  = 
| solubility  = 
| diaphaneity = Opaque
| other       = weakly magnetic
| 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>
}}

'''Jacobsite''' is a [manganese](/source/manganese) [iron](/source/iron) [oxide mineral](/source/oxide_mineral). It is in the [spinel](/source/spinel) group and forms a [solid solution](/source/solid_solution) series with [magnetite](/source/magnetite). The chemical formula is (Mn,Mg)Fe<sub>2</sub>O<sub>4</sub> or with [oxidation states](/source/Redox) and substitutions: 
(Mn<sup>2+</sup>,Fe<sup>2+</sup>,Mg)(Fe<sup>3+</sup>,Mn<sup>3+</sup>)<sub>2</sub>O<sub>4</sub>.<ref name=Handbook/><ref name=Webmin>[http://www.webmineral.com/data/Jacobsite.shtml Webmineral data] </ref>
[[File:Jacobsite-d05-134a.jpg|thumb|left|Jacobsite, N'Chwaning Mines, [Kuruman](/source/Kuruman), Kalahari manganese fields, [Northern Cape Province](/source/Northern_Cape_Province), South Africa. Size 3.8 x 3.5 x 3.2 cm]]
{{clear left}}
It occurs as a primary phase or as alteration of other manganese minerals during [metamorphism](/source/metamorphism) of manganese deposits.<ref name=Webmin/> Typical associated minerals include [hausmannite](/source/hausmannite), [galaxite](/source/galaxite), [braunite](/source/braunite), [pyrolusite](/source/pyrolusite), [coronadite](/source/coronadite), [hematite](/source/hematite) and magnetite.<ref name=Handbook/> It is a [ferrimagnetic](/source/ferrimagnetic) substance, which is weakly attracted by a magnet.

It was first described in  1869 and named for the Jakobsberg Mine, [Nordmark](/source/Nordmark%2C_Sweden), [Filipstad](/source/Filipstad), [Värmland](/source/V%C3%A4rmland), [Sweden](/source/Sweden).<ref name=Mindat/>

==References==
{{Reflist}}

*[https://web.archive.org/web/20060301151751/http://www.npi.gov.au/database/substance-info/profiles/52.html National Pollutant Inventory - Manganese and compounds Fact Sheet]

{{-}}
Category:Spinel group
Category:Iron(II,III) minerals
Category:Manganese(II,III) minerals
Category:Magnesium minerals
Category:Magnetic minerals
Category:Cubic minerals
Category:Minerals in space group 227
Category:Minerals described in 1869

{{oxide-mineral-stub}}
{{Manganese minerals}}

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Adapted from the Wikipedia article [Jacobsite](https://en.wikipedia.org/wiki/Jacobsite) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Jacobsite?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.