Typically the right answer is the obvious answer.
Earth and metal manipulation are obvious, buffs that make other dwarves better at fighting, enchanting gear but that's not usually an option in D&D, Even divining could be a decent fit.
To put it in game terms for D&D because that's what most people play.
Dwarven mages would be wizards they don't really have many sorcerer bloodlines.
The wizards would probably specialize in Conjuration, Abjuration, Transmutation, and occasionally Divination, there might be an odd Evoker or two as well but almost zero Necromancers, Illusionists, or Enchanters.
Dwarven clerics would probably outnumber arcane casters and mostly focus on the same schools, however dwarves are typically very traditional and dwarven clerics would be more focused on casting spells from their domain/deity.
Rune magic isn't really a type of magic as it is an aesthetic and while it fits dwarves it doesn't really mean anything other than dwarven magic looks different.