The atomic-scale surface structure of many oxides and minerals remains unresolved despite its decisive role in surface chemistry and reactivity. Noncontact atomic force microscopy (nc-AFM) enables atomically resolved imaging of insulating surfaces, and when combined with controlled tip functionalization, provides chemical identification of individual surface atoms. In recent work [1], we applied this approach to unravel the reconstructed sapphire Al2O3(0001) surface. Using nc-AFM with a precisely controlled tip apex, we directly resolved the positions of individual Al and O atoms and disproved the long-standing assumption that the reconstructed alumina surface is metallic. Instead, our results show that the extensive reconstruction is driven by increased coordination of surface Al cations while preserving overall Al2O3 stoichiometry. A related mechanism emerges for the ternary spinel oxide MgAl2O4(001). In its bulk-terminated form this surface is polar and unstable. We show that it adopts a c(2 × 4) reconstruction with modified near-surface stoichiometry, in which ordered pairs of octahedral Mg cations replace tetrahedral bulk sites. This redistribution of cations compensates the macroscopic dipole moment and stabilizes the surface. The resulting octahedral cation-pair motif closely resembles those found on other spinel (001) surfaces, suggesting a universal mechanism of polarity compensation in this materials class. Finally, we highlight the versatility of nc-AFM through atomic-scale studies of water at the surfaces of cleaved gypsum (CaSO4·2H2O) and silver iodide (AgI), a widely used ice-nucleating material in cloud seeding. Although the basal planes of AgI lattice-match with ice, they are polar and cannot exist in a bulk-terminated form. We show that AgI surfaces undergo surface reconstructions, and that the atomic details of these reconstructions determine ice nucleation behavior [2]. [1] J.I. Hütner, et al., Science 385, 1241–1244 (2024) [2] J.I. Hütner, et al., Science Advances 11, 44, eaea2378 (2025)