What geologic process change granite igneous rock into gneiss metamorphic rock?
Granite can be changed into gneiss through the process of metamorphism, where heat and pressure alter the mineral structure of the rock. This process causes the minerals in the granite to recrystallize, forming distinct banding and foliation characteristic of gneiss. The original minerals in the granite are reorganized into new minerals such as mica, quartz, and feldspar, giving gneiss its unique appearance.