In commemoration of the 150th anniversary of Derby's birthday a brief review of his work has been presented. From 173 scientific works, Derby published 7 papers on the Manganese deposits in the period 1898-1908. In two of these papers, Derby defined the manganese protore "queluzite", consisting of spessartite garnet, amphibole and rhodochrosite and tephroite, later recognized by Hussak. In this work we tried to compare the Derby's descriptions with our thermodynamic studies applied to the equilibrium conditions, controlled by the chemicals potentials of SiO2 and CO2 in the protore.
manganese; queluzito; Conselheiro Lafaiete; Orville Derby
