The study of soil minerals structure has been conducted in the Sawaru village, Maros regency, South Sulawesi which is locally known to be the landslides-prone area. The aim of this research is basically to determine the mineral characteristics of the soil. The samples were taken randomly in three points with a depth of 75 cm at point 1 and 100 cm for the other. The structure of the samples was analyzed using X-Ray Diffraction (XRD) where the samples were placed in the high temperature and airtight containers. The results of XRD analysis showed that minerals contained at point 1 (75 cm in depth) were illite (69.3%) with a monoclinic structure, albit mineral (25.6%) with a triclinic structure and kaolinite (5.0%) with a triclinic structure. Samples at point II (100 cm depth) contained illite (67.2%), feldspar (23.9%) with monoclinic and merrillit (8.9%) with trigonal structures. Samples at point III (100 cm in depth) contained illite (55.9%), bobtraillite (22.2%) with a trigonal structure and feldspar (21.9%) with a monoclinic structure. The minerals observed at the sampling points are dominated by illite which is clay in nature. Such a mineral has been known to have an ability to initiate high plasticity in soil, leading to the slope instability.