Caseyite
Caseyite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula [(V⁵⁺O₂)Al₇.₅(OH)₁₅(H₂O)₁₃]₂[H₂V⁴⁺V⁵⁺₉O₂₈][V⁵⁺₁₀O₂₈]₂·90H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/n). It is a member of the Pascoite structural group.
Key properties: Mohs hardness 2–3; specific gravity 2.151; Pale yellow streak; Vitreous luster; optically biaxial.
IMA symbol Csy, IMA status: approved, named in 2019.
A secondary mineral formed by oxidation in a moist, low-temperature, post-mining environment from montroseite-corvusite and/or asphaltum assemblages on sandstone in a Colorado Plateau type, roll-front uranium/vanadium deposit.
It is found associated with Gypsum, barite (West Sunday mine), huemulite (Packrat mine), postite (Burro mine), montroseite, corvusite.
The mineral was named to honor the American geochemist William H. Casey (b. 1955), Distinguished Professor in the Departments of Chemistry and Earth & Planetary Sciences, University of California.