The spinel-group minerals are widely distributed in nature. They are important components of many metamorphic and ignious rocks. In this group, spinel (MgOAl2O3) and chromium spinel (MgO-Cr2O3) are the most important minerals applied in industry. This paper introduces the latest progress of some studies of mineralogical features of spinels. Some basic theories and principles of spinel formation and the basic technology and process of industrial production of spinel minerals are described. The development and application of raw minerals and products of spinels are also briefly introduced.