What is the difference between muscovite mica and phlogopite mica?

Muscovite Mica is a potassium-aluminium based alumino-silicate while Phlogopite Mica is a potassium-magnesium based alumino-silicate. The aluminium content in muscovite is higher than in phlogopite. Alternatively, the magnesium content in phlogopite is much higher than in muscovite.