The crystal structures of two marialite samples (S-1 and S-2) with the meionite component (9.6 and 17.0%, respectively) and the compositions (Na_3.35Ca_0.38K_0.24)_Σ3.97(Si_8.78Al_3.22F³⁺ _0.01)_Σ1.01O₂₄Cl_0.92 and (Na_3.21Ca_0.68K_0.11) _Σ3.90(Si_8.56Al_3.44F³⁺ _0.01)_Σ1.01O₂₄Cl_0.90, respectively, from the Kukurt deposit (the Pamirs, Tadzhikistan) were refined using the X-ray powder diffraction data by the Rietveld method. The chemical compositions of the samples S-1 and S-2 correspond to the discontinuity in the existence region of the marialite-meionite solid solution. The structures of S-1 and S-2 marialites were refined in the anisotropic/isotropic approximation (the Pearson function) to the reliability factors R_p = 4.80 and 5.00, R_wp = 6.10 and 6.50, R_B = 3.70 and 3.50, R_F = 4.70 and 4.90; s = 1.39 and 1.28, respectively. The unit-cell parameters were determined as a = 12.049(1) Å, c = 7.5670(8) Å, V = 1098.49(2) ų for S-1 and a = 12.037(1) Å, c = 7.5535(1) Å, V = 1097.18(1) ų for S-2, the sp. gr. I4/m, Z = 2. The analysis of the X-ray diffraction data allowed the refinement of the trend in the behavior of the unit-cell parameters depending on the composition of the Si-Al-O framework of scapolite.