rockbridgeite

{{Infobox mineral | name = Rockbridgeite | category = | boxwidth = 24 | boxbgcolor = | image =Phosphosiderite-Rockbridgeite-k330a.jpg | caption = | formula = Fe2+Fe3+4(PO4)3(OH)5 | IMAsymbol = Rkb | molweight = 648.96 g/mol | strunz = 8.BC.10 | dana = 41.9.2.1 | system = Orthorhombic | class = Dipyramidal (2/m2/m2/m) (same H-M symbol) | symmetry = Bbmm | color = Varies from green, to black, to brownish green, to reddish brown | habit = Euhedral crystals rare; typically fibrous in crusts, botryoidal and drusy masses | twinning = Cruciform twins possible | cleavage = Perfect on {100}, Distinct on {010}, Distinct on {001} | fracture = Uneven | tenacity = Brittle | mohs = 4.5 | luster = Vitreous to dull | refractive = Nx = 1.875, Ny = 1.880, Nz = 1.897 | opticalprop = Biaxial (+) | birefringence = 0.0220 | pleochroism = (x): light brown to light yellow-brown (y): bluish green. (z): dark bluish green. | streak = Greenish gray | gravity = 3.40 | melt = | fusibility = | diagnostic = | solubility = Soluble in HCl, but not in HNO3 or H2SO4 | diaphaneity = Subtranslucent | other = | references = }}

Rockbridgeite is an anhydrous phosphate mineral in the "Rockbridgeite" supergroup with the chemical formula Fe2+Fe3+4(PO4)3(OH)5. It was discovered at the since-shut-down Midvale Mine in Rockbridge County, Virginia, United States. The researcher who first identified it, Clifford Frondel, named it in 1949 for its region of discovery, Rockbridge County.