10 motes of fire is about 10g on my server..but my engineer uses them to make stuff like gunpowder (for leveling up). Talk about throwing money down the drain.
Besides that, I think I saw JC recipes with a need for primal fire and primal earth. So they are used for these kinds of recipes.. If you have no other use for it, save a stack or two for when you find out why you need it, and then just sell the rest and make money off it.