{{Infobox mineral | name = Ludwigite | category = Borate mineral | boxwidth = | boxbgcolor = | image = Ludwigite-242641.jpg | imagesize = 260px | caption = Radial aggregates of lustrous, black, metallic, acicular ludwigite crystals to 0.5 cm, from Alta Stock, Salt Lake County, Utah, USA. | formula = Mg<sub>2</sub>Fe<sup>3+</sup>BO<sub>5</sub> | IMAsymbol = Ldw<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 = 195.26 g/mol | strunz = 6.AB.30 | system = Orthorhombic | class = Dipyramidal (mmm) <br/>H-M symbol: (2/m 2/m 2/m) | symmetry = ''Pbam'' | unit cell = a = 9.26, b = 12.26 <br/>c = 3.05&nbsp;[Å]; Z&nbsp;=&nbsp; | color = Pitch-black, olive-black | habit = Massive – fibrous commonly in fanlike to felted aggregates | cleavage = [001] Perfect | fracture = Brittle – Conchoidal – Very brittle fracture producing small, conchoidal fragments. | mohs = 5.5 | luster = Silky to submetallic | refractive = n<sub>α</sub> = 1.830 – 1.850 n<sub>β</sub> = 1.830 – 1.850 n<sub>γ</sub> = 1.940 – 2.020 | opticalprop = Biaxial (+) | birefringence = δ = 0.110 – 0.170 | pleochroism = X = Y = dark green; Z = dark reddish brown | 2V = Measured: 20° to 45° | streak = Greenish black | gravity = 3.6 – 3.8 | melt = | fusibility = | diagnostic = | solubility = Slowly soluble in acid | diaphaneity = Opaque, translucent in thin fragments | alteration = limonite | references = <ref name=Mindat/><ref name=Handbook>[http://rruff.geo.arizona.edu/doclib/hom/ludwigite.pdf Handbook of Mineralogy]</ref> }}

'''Ludwigite ''' is a magnesium-iron borate mineral: Mg<sub>2</sub>FeBO<sub>5</sub>.

Ludwigite typically occurs in magnesian iron skarn and other high temperature contact metamorphic deposits. It occurs in association with magnetite, forsterite, clinohumite and the borates vonsenite and szaibelyite.<ref name=Handbook/> It forms a solid solution series with the iron(II)-iron(III) borate mineral vonsenite.<ref name=Mindat/>

It was first described in 1874 for an occurrence in Ocna de Fier, Banat Mountains, Caraș-Severin County, Romania and named for Ernst Ludwig (1842–1915), an Austrian chemist at the University of Vienna.<ref name=Mindat>[http://www.mindat.org/min-2454.html Ludwigite on Mindat.org]</ref> [[File:Forsterite-Ludwigite-34581.jpg|thumb|left|Ludwigite needles and sprays as inclusions in a peridot crystal from Sapat Gali, Kohistan District, Pakistan. Size 2.8 x 2 x 1.1 cm.]] {{clear}}

==References== {{Commons category}} {{Reflist}}

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Category:Magnesium minerals Category:Iron(III) minerals Category:Borate minerals Category:Orthorhombic minerals Category:Minerals in space group 55

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