[quote=@KnightofTempest]
Sure I just figured since it was an Earthbender thing in Legend of Korra, I could get away with it, it is technically molten rock after all. Will edit though
[/quote]

Yeah, I can totally see why lava could be controlled with an Earth gem. But for the sake of keeping things in balance, I have to say no.
Although, if you think about it, lava is actually a mix of both earth and fire, so maybe we can spice things up, and say lava can only be manipulated with the power of two gems simultaneously.