Case with chemical mini-laboratory for field use, belonging to Claude-Henri Gorceix, director of the Escola de Minas de Ouro Preto between 1876 and 1891, containing flasks of acid reagents, reducers and other substances used in the identification of mineral samples. At that time, “docimasy”, the part of chemistry that seeks to determine the proportion in which metals enter in ores, was one of the most important subjects of the mineralogy course. Collection of the Museu de Ciência e Técnica of the Escola de Minas of the Universidade Federal de Ouro Preto. Photograph taken by Marcelo Lerner.