Orange crystals of the extremely rare mineral ferrivauxite (IMA 2014-003) from the type and only known locality worldwide: Siglo XX Mine, Llallagua, Potosi Department, Bolivia. Ferrivauxite is the oxidized equivalent of vauxite (Fe3+ for ferrivauxite and Fe2+ for vauxite). — Photo: David Hospital · CC BY-SA 4.0
Ferrivauxite
Ferrivauxite is an IMA-recognized mineral species in the phosphate class, with the chemical formula Fe³⁺Al₂(PO₄)₂(OH)₃·5H₂O.
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Vauxite structural group.
Key properties: Mohs hardness 3.5; specific gravity 2.4; Pale yellow-brown streak; Vitreous luster; optically biaxial.
IMA symbol Fvx, IMA status: approved, named in 2014.
produced through oxidation of primary fluorapatite and other phosphates in a hydrothermal tin deposit.
It is found associated with Sigloite, crandallite.
Emphasizes that the mineral is an oxidized equivalent (ferric analog) of vauxite. The latter honors George Vaux Jr (1863-1927), American lawyer and mineral collector.