{{Short description|Phosphate mineral}} {{Infobox mineral | name = Triploidite | boxwidth = | boxbgcolor = | image = Triploidite-199681.jpg | imagesize = 200px | alt = | caption = Radial reddish triploidite from the Branchville Quarry, Branchville, Fairfield County, Connecticut, US (7.0 x 4.8 x 2.6 cm) | category = Phosphate minerals | formula = {{chem2|(Mn,Fe)2PO4OH}} | IMAsymbol = Tpd<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 = 8.BB.15 | dana = | system = Monoclinic | class = Prismatic (2/m) <br/><small>(same H-M symbol)</small> | symmetry = ''P''2<sub>1</sub>/a | unit cell = a = 12.36&nbsp;Å, b = 13.27&nbsp;Å <br/>c = 9.94&nbsp;Å; β = 108.23°; Z&nbsp;=&nbsp;16 | color = Red-brown, light pink, yellow-brown; light pink to light brown in transmitted light. | colour = | habit = Elongated and striated prismatic crystals; fibrous: columnar to spherulitic | twinning = | cleavage = On {010}, good; on {120}, fair; on {110}, very poor. | fracture = Uneven to subconchoidal | tenacity = | mohs = {{frac|4|1|2}} – 5 | luster = Adamantine, vitreous, greasy | streak = White, off-white. | diaphaneity = Transparent, translucent | gravity = 3.70 measured | density = | polish = | opticalprop = Biaxial (+) | refractive = n<sub>α</sub> = 1.725 n<sub>β</sub> = 1.726 n<sub>γ</sub> = 1.730 | birefringence = δ = 0.005 | pleochroism = Weak | 2V = | dispersion = r > v strong | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = Soluble in acids. | impurities = | alteration = | other = | prop1 = | prop1text = | references = <ref name=Handbook/><ref name=Mindat/><ref name=Webmin/> }}

'''Triploidite''' is an uncommon manganese iron phosphate mineral with formula: {{chem2|(Mn, Fe)2PO4OH}}. It crystallizes in the monoclinic crystal system and typically occurs as elongated and striated slender prisms which may be columnar to fibrous. Its crystals may be pinkish to yellowish brown or red-orange.<ref name=Handbook>[http://rruff.geo.arizona.edu/doclib/hom/triploidite.pdf Handbook of Mineralogy]</ref>

It was first described in 1878 for an occurrence in the Branchville Quarry, Branchville, Fairfield County, Connecticut. The name is derived from its resemblance to triplite.<ref name=Mindat>[http://www.mindat.org/min-4022.html Mindat]</ref>

It typically occurs as a hydrothermal alteration product of primary phosphate minerals in granite pegmatites. It occurs with triplite, lithiophilite, triphylite, eosphorite, dickinsonite and rhodochrosite.<ref name=Handbook/><ref name=Webmin>[http://webmineral.com/data/Triploidite.shtml Webmineral data]</ref>

It forms a solid solution series with the iron rich wolfeite.<ref name=Mindat/><ref name=Webmin/>

==See also== {{Portal|Earth sciences}} * Classification of minerals * List of minerals

==References== {{commons category| Triploidite}} {{Reflist}}

{{Manganese minerals}}

Category:Manganese(II) minerals Category:Iron(II) minerals Category:Phosphate minerals Category:Monoclinic minerals Category:Minerals in space group 14

{{Phosphate-mineral-stub}}