phosphosiderite

{{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 FePO4·2H2O| IMAsymbol = Phsd|system=Monoclinic|class=Prismatic 2/m|symmetry=P21/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=nα = 1.692 nβ = 1.725 nγ = 1.738|birefringence=0.046|pleochroism=Visible|2V=Measured: 62°, Calculated: 62°|dispersion=Very strong 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.