{{Short description|Phosphate mineral}} {{Infobox mineral|boxwidth=|boxtextcolor=black|boxbgcolor=#dda0dd|name=Phosphosiderite|image=Phosphosiderite-141096.jpg|caption= Red phosphosiderite between violet strengite. Picture width 4 mm.|category=Phosphate minerals|formula=Hydrated iron phosphate FePO<sub>4</sub>·2H<sub>2</sub>O| IMAsymbol = Phsd<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>|system=Monoclinic|class=Prismatic 2/''m''|symmetry=''P2<sub>1</sub>/n'' (no. 14)|unit cell=454.76 ų|molweight=186.85|color=Usually red to pink to purple, sometimes green, usually yellow veined|habit=Tabular {010} or stout prismatic [001]|twinning=Common on {101}, typically as interpenetration|cleavage={010} Distinct, {001} Indistinct|fracture=Uneven|mohs=3.5–4|luster=Vitreous|opticalprop=Biaxial (−)|refractive=n<sub>α</sub> = 1.692 <br/>n<sub>β</sub> = 1.725 <br/>n<sub>γ</sub> = 1.738|birefringence=0.046|pleochroism=Visible|2V=Measured: 62°, Calculated: 62°|dispersion=Very strong <br/>r > v|streak=White|gravity=2.74–2.76|density=2.74 – 2.76 measured, 2.76 calculated|solubility=Totally soluble in hydrochloric acid, nearly insoluble in nitric acid|diaphaneity=Transparent, translucent }}
'''Phosphosiderite''' is a rare mineral named for its main components, phosphate and iron. The siderite at the end of phosphosiderite comes from the word "sideros", the Greek word for iron. It was published in 1890, and has been a valid species since pre-IMA. It is an IMA approved mineral which got grandfathered, meaning its name is still believed to refer to an existing species.<ref name=":0">{{Cite web |title=Phosphosiderite |url=https://www.mindat.org/min-3187.html |access-date=2022-10-21 |website=www.mindat.org}}</ref>
== Properties == Phosphosiderite is a member of the metavariscite group,<ref name=":0" /> and probably forms a complete series with metavariscite. It is the dimorph of strengite.<ref name=":1">{{Cite web |title=Phosphosiderite – Encyclopedia |url=https://www.le-comptoir-geologique.com/phosphosiderite-encyclopedia.html |access-date=2022-10-21 |website=www.le-comptoir-geologique.com}}</ref> It is totally soluble in Hydrochloric acid and nearly insoluble in nitric acid.<ref>{{cite web |title=Phosphosiderite |url=https://nationalgemlab.in/phosphosiderite/ |website=National Gem Lab |date=18 March 2017}}</ref> It is usually cut into a cabochon shape for jewelry, and used as an ornamental stone.<ref name=":1" /> It mainly consists of oxygen (51.38%), iron (29.89%) and phosphorus (16.58%), but contains hydrogen (2.16%) as well.<ref>{{Cite web |title=Phosphosiderite Mineral Data |url=http://www.webmineral.com/data/Phosphosiderite.shtml |access-date=2022-10-21 |website=www.webmineral.com}}</ref>
== Colors == Phosphosiderite is often found in a bright orchid-purple tint with yellow-colored streaks. The vein-like streaks found in the stone are known as cacoxenite. Four other rare color variants are rose red, brown-reddish yellow, mossy green, and dark shades of purple. Phosphosiderite can also be found as a colorless mineral.<ref name=mindat/> It is pleochroic; on the X axis around 4° it is light rose, on the Y axis it is carmine red, and on Z it is colorless.<ref name=mindat>{{Cite web|title=Phosphosiderite|url=https://www.mindat.org/min-3187.html|access-date=2021-03-05|website=www.mindat.org}}</ref>
== Occurrences and localities == Phosphosiderite is mined in some parts of Chile, Argentina, Germany, Portugal, and the United States. It occurs in association with strengite, turquoise, triphylite, leucophosphite, huréaulite, barbosalite and laueite.<ref name=":2">{{Cite journal |title=Phosphosiderite |url=http://www.handbookofmineralogy.org/pdfs/phosphosiderite.pdf |journal=Handbook of Mineralogy}}</ref> In zoned granitic pegmatites, it usually occurs as an alteration product of primary phosphates. This makes it a secondary phosphate.<ref name=":1" /> It may be replacing shells and bones, and can occur in the soil as a component of it as well.<ref name=":2" /> However, the latter is rarer.<ref name=":1" />
== References == {{reflist}}
Category:Monoclinic minerals Category:Minerals in space group 14 Category:Phosphate minerals