What's the difference between mafic and felsic?

Mafic is used for silicate minerals, magmas, and rocks which are relatively high in the heavier elements. Felsic, on the other hand, is used for silicate minerals, magmas, and rocks which have a lower percentage of the heavier elements, and are correspondingly enriched in the lighter elements, such as silicon and oxygen, aluminum, and potassium.

Mafic rocks are rich in iron and magnesium. Felsic rocks are rich in the mineral silicon and aluminum