Fe-rich fayalite slag (FS) is an attractive low-clinker precursor for alkali-activated construction materials, yet its ambient-temperature reactivity is intrinsically limited. A recent ambient-cured mortar study demonstrated that replacing 20 wt.\% of FS with blast furnace slag (BFS) or ladle slag (LS) strongly improves kinetics, strength, ultrasonic pulse velocity, and resistance to water ingress. The present article interrogates the same three mortar systems — AAFS, AAFS-BFS, and AAFS-LS — through a different analytical lens focused on binder-gel heterogeneity rather than only average composition. The analysis integrates the reported experimental matrix, the published EDS ternary point clouds, the reported atomic ratios, and the accompanying phase and performance descriptors. Ternary point clouds from the reported EDS diagrams were reconstructed by a reproducible image-based digitization workflow, normalized in simplex-consistent coordinates, and quantified using centroid displacement, convex-hull area, and covariance-ellipse spread. The resulting compositional fields reveal distinctions that are not captured adequately by mean ratios alone. In the Ca-Al-Si plane, AAFS occupies a narrow Si-rich domain, whereas AAFS-BFS shifts toward a Ca-rich field and AAFS-LS exhibits the broadest Ca-Al-bearing distribution, with a hull area about 8.9 times that of AAFS. In the Na-Fe-Si plane, AAFS remains Fe-enriched with an elongated tail, AAFS-BFS concentrates in a compact Si-dominant field, and AAFS-LS occupies an intermediate Na-bearing domain. These compositional patterns align with the reported calorimetric acceleration, the emergence of C-(A)-S-H/C-(N)-A-S-H signatures alongside Fe-bearing gel participation, and the superior transport-related performance of the blended mortars. As a secondary analytical study based on published measurements, the field metrics are interpreted conservatively as robust descriptors of relative heterogeneity rather than as substitutes for raw point-wise EDS export.