Vauxite Locality: Siglo Veinte Mine (Siglo XX Mine; Llallagua Mine; Catavi), Llallagua , Rafael Bustillo Province , Potosí Department , Bolivia ( Locality at mindat.org ) An aesthetically shaped crust of sparkly, tiny dark-blue vauxite crystals from the Type Locality, the Siglo XX Mine of Bolivia. Vauxite is an ultra-rare phosphate. Ex Marty Zinn Collection. 3.5 x 3.0 x 1.0 cm — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Vauxite
A sky-blue iron-aluminium phosphate of the paravauxite subgroup — a Bolivian specialty.
Intro adapted from Wikipedia (CC BY-SA).
Vauxite is an IMA-recognized mineral species in the phosphate class, with the chemical formula Fe²⁺Al₂(PO₄)₂(OH)₂·6H₂O.
It crystallizes in the triclinic crystal system (space group P-1).
Key properties: Mohs hardness 3.5; specific gravity 2.39–2.4; White streak; Vitreous luster; refractive index 1.556; optically biaxial.
IMA symbol Vx, grandfathered status — known before the IMA’s founding, named in 1922.
A secondary mineral derived from alteration of apatite.
It is found associated with Wavellite, paravauxite (Llallagua, Bolivia); marcasite, wavellite (Huanuni, Bolivia).
The mineral was named to honor George Vaux, Jr. (1863–1927), American lawyer and mineral collector, Bryn Mawr, Pennsylvania, USA.