Abstract: X-ray powder diffraction (XRD) patterns for many interstratified mica/glycolated smectites were calculated by changing combinations of probabilities and transition probabilities of two-component layers. Three basal XRD reflections, 5.1°–7.6°2θ (p1), 8.9°–10.2°2θ (p2), and 16.1°–17.2°2θ (p3) were selected for the quantification curves. A distinct relationship exists between Δ2θ1 (p2 - p1) and Δ2θ2 (p3 - p2) which shows systematic changes with expandability at constant Reichweite values. The calculated values were plotted with Δ2θ1 and Δ2θ2 as the axes of coordinates, and quantification curves were calculated. The components and stacking parameters of mica/smectites were estimated easily using this diagram. Probabilities of existence of component layers and their transition probabilities for Reichweite (R=0) and (R=1) structures, and special cases of R=2 and R=3 structures were obtained.