**Abstract**

The parameters of unit cell, structure, refractive index, solubility data, PO4/CO3 ratio, surface area, etc., are important parameters for characterization of phosphate rocks. Third chapter of this book introduces methods for identification, characterization and properties of apatites in four main sections. The first part describes techniques used for identification and investigation of properties of phosphate minerals, including X-ray diffraction analysis, powder neutron diffraction, X-ray fluorescence as well as spectroscopic and microscopic methods. Some of these techniques are then demonstrat‐ ed on the fluorapatite specimen in the second part. The third part of this chapter deals with thermodynamic properties of apatite-type compounds and introduces some of thermodynamic predictive methods. The fourth part is dedicated to dissolution of apatite, where the reaction between solids and liquids according to different dissolu‐ tion models is described. Chapter ends with methods for the evaluation of reactivity of phosphate rocks.

**Keywords:** Apatite, Carbonate to Phosphate Ratio, Dissolution of Apatite, Reactivity of Apatite, Citrate Solubility
