Magmatic rocks of Western Sicily display spheroidal coarse-grained aggregates (enclaves) of leucocratic minerals, identical in both composition and zoning to minerals in the surrounding rock. Liquid immiscibility phenomena are indicated by immiscible glass globules in each other and confirmed by exploratory melting experiments. Moreover, detailed mineralogy indicates that the Sicilian enclaves originated as immiscible felsic liquids that separated from a basic magma, and rule out the other possibility that they are formed by mixing of two liquids generated independently one from the other. This study provides a basis for interpreting the cooling history of the two-liquid Sicilian magma. Our results strongly support Lucido's (1990) theory according to which, in time, as the temperature of a critical basic magma decreases, a liquid-liquid phase separation in an acidic sense occurs.