Once the Sorcerer has mastered the 4 prime elements he will be able to begin combining them. The 4 base elements you know. The 4 para-elements are:
Magma - Earth and Fire
Mud - Earth and Water
Ice - Water and Air
Smoke - Fire and Air
There are more combinations that are know to exist but the knowledge of them has been lost. Search as they might the Sorcerers have not recovered all that was lost to them. Ancient manuscripts tell of Sorcerer's who could combine more than 2 elements, creating powerful quasi-elements. There is much to be discovered.