The Elements

Each element has varying degrees of how common it is for a mage of that kind to appear. The rarest ones are at the bottom, and the most frequently-occurring are at the top.

Earth:
Stone Mage
Plant Mage
Quake Mage

Water:
Water-Seeker
Tidal Mage
Tempest Mage

Air:
Weather Mage
Wind Mage
Storm Mage

Fire:
No sub-category; they're very rare in and of themselves, and fire is fire. It burns stuff!

Spirit:
Illusionist
Animal Mage
Healer
Seer