Herein, raw black limestone (RBL) and its activated form at 450 °C/5 h (ABL) were characterized and tested as adsorbents for phosphate and crystal violet (CV) at pH (2.0–10.0). The two adsorbents displayed nearly the same efficiency for phosphate uptake, while RBL was more effective for CV. Isotherm studies at 298–318 K indicated that Langmuir, Freundlich, and Dubinin–Radushkevich models described well the uptake results without determination of the physicochemical parameters governing phosphate and CV adsorption mechanisms. The application of five advanced statistical models (ASM) indicated that monolayer with one energy and monolayer with two energies fitted well the phosphate and CV adsorption, respectively. Phosphate adsorption was controlled by multi–docking mechanism, while multi–docking and multi‒molecular mechanisms were involved in CV uptake onto the RBL. The density of receptor sites (NM) was resulted to be an important factor controlling the phosphate and CV adsorption capacities. With temperature, the NM values increased from 149.62 to 215.52 mg/g and decreased from 340.13 to 208.97 mg/g for phosphate and CV, respectively. This confirmed the significant role of organic carbon interactions as n–π and π–π in enhancement of CV uptake. The adsorption energies exhibited the physical nature of the adsorption processes as endothermic and exothermic reactions for phosphate and CV, respectively. Thermodynamic studies confirmed the spontaneous nature of the phosphate and CV adsorption onto RBL. Based on this study, it can be concluded that RBL is an excellent and low–cost adsorbent for water contaminants, especially organic dyes. Furthermore, the interpretations of steric and energetic parameters indicated that the adsorption performance of RBL is mainly related to its organic carbon content.