Practical laboratory activity on mesoscopic rock samples aimed at recognizing, describing and classifying sedimentary (terrigenous siliciclastic, carbonate, evaporitic, siliceous, residual, hydrocarbons and coals), magmatic (intrusive and extrusive) and metamorphic rocks. The recognition is done by naked eye, with the aid of simple tools such as geologist hummer and lens, steel pick, ruler, diluted hydrochloric acid, water. The recognition and classification of the different types of sedimentary rocks is preceded by theoretical lessons on classification criteria and schemes according to the most common international geologic practice.