The crystal structure of a rare supergene mineral kuznetsovite Hg₃(As0₄)Cl, previously determined from powder data, is refined (space group P2₁3, a = 8.379(3) å, V = 588.3(4) å⁰³, Z = 4, d_calc = 8.763 glcm³, 3.44 < θ < 24.96‡, 563 I_hkl(msd)/211 I_hkl(indep), R₁ = 0.0997, wR₂ = 0.2515). It is formed from the Cl⁻ and (AsO₄)^3- anions (As-O 1.74(3) and 1.79(1) å) and the trigonal cations Hg ₃ ⁴⁺ (Hg-Hg 2.675(5) å, HgHgHg 60‡). The coordination polyhedron around each mercury atom involves two mercury atoms, two oxygen atoms at short Hg-0 distances (2.17(3) and 2.28(3) å, < OHgO 94.3(13)‡), and more remote oxygen and chlorine atoms (Hg-0 2.601(6) å, Hg-Cl 2.838(9) å). The polyhedron is irregular and close to a trigonal antiprism. The Hg₃ triangles alternate with AsO₄ tetrahedra along each coordinate axis. Taking into consideration only short Hg-0 bonds (2.17(3) and 2.28(3) å), one can isolate a framework with chlorine ions lying in the cavities.