[whswhs]

In one of my campaigns, I went with the idea of dwarves as mineral intelligences (sort of supported by Tolkien's account of Aule's construction of the first seven dwarves). This led me to the concept of dwarf lineages or guilds with affinities for the seven states of "mineral": sand (glassworkers), soil (farmers and civil engineers), clay (potters and brickmakers), stone (masons), metal (smiths), gem (gemcutters and enchanters), and dwarf (rulers and judges). You're welcome to steal that if you think it would be useful.

There is no such list in Tolkien. In fact there's no explicit discussion of what any of the rings of power can do, except the One, though it's possible to infer that the Three provide the powers of fire, air, and water. So what you need is a plausible original fiction, I think.