Granitic magma primarily crystallizes to form granite and is composed of several key minerals. The minerals that crystallize from granitic magma over the temperature range of approximately 640°C to 930°C include:
- Quartz - Typically crystallizes last as the magma cools.
- Feldspar - This includes both plagioclase and potassium feldspar (orthoclase or microcline) which crystallize at higher temperatures.
- Biotite - A dark mica that crystallizes in this temperature range as well.
- Muscovite - A lighter mica that may form later, but can overlap with the biotite crystallization.
- Amphibole - If present, can form as the magma cools.
When granitic magma completely crystallizes into granite, the resulting rock typically belongs to the granite facies of the granulite metamorphic facies if it undergoes metamorphism under high temperature and pressure conditions without significant fluid activity. However, granite itself is often considered more in the context of igneous rocks rather than metamorphic facies directly.
In summary, the minerals crystallizing from granitic magma in the specified temperature range include quartz, feldspar (both plagioclase and potassium), biotite, muscovite, and possibly amphibole. The final crystallized rock, granite, can exist within the granulite metamorphic facies under high-grade metamorphic conditions.