The crystal structure of mitryaevaite, Al₅(PO₄)₂[(P,S)O₃(OH,O)]₂F₂(OH)₂(H₂O)₈·6.48H₂O, a secondary mineral from the alteration zone of carbonaceous. vanadium-bearing shales from northwestern Karatau Range and Zhabagly Mountains, southern Kazakhstan, has been determined from a microcrystal (8 × 10 × 65 μm) using synchrotron X-radiation. The structure was solved by direct methods and refined to RI = 0.057 and S = 1.020 using 2 I I I unique observed reflections (F_o ≥ 4σ_F). The structure is triclinic, space group PĪ, a 6.918(1). b 10.127(2). c 10.296(2) Å, α 77.036(3), β 73.989(4), Υ 76.272(4)°. V 663.8(2) ų, Z = 1. The structure of mitryaevaite contains five-membered finite chains of corner-sharing (AlΦ₆) octahedra. The chains are cross-linked via (PO₄) tetrahedra to produce complex slabs that are parallel to the a axis. and that are in turn linked through additional (PO₄) tetrahedra to form layers parallel to the (011̄) plane. The heteropolyhedral layers are linked together through hydrogen bonds to H₂O groups located in the interlayer region.