This question has been in the back of my mind since I read it. It sounds familiar and I think you may find something within the Space Master books, perhaps with the psion users and semi-psion users. I'll have to dig out the books and take a look.
RM2 also has the Alchemy Companion and I'll take a look in that book to see what is there. That deals with the manipulation and enhancement of matter.
However... this also got me thinking because the title of your post conjured up images of a spell caster using powder as a means of focus. Our gaming setting is restricted to the magics only found in Elemental Companion and Alchemy Companion. The setting is similar to the Renaissance Period of our own real world. "Science" rules all, even what passes for science. People are enlightened, Alchemy is the new science and Elementalism is the newest discovery.
Going back to the idea of a Powder Mage, I was thinking "dust" could be an element that players could craft a PC around. There are the primary elements, then secondary and tertiary elements. Depending on the school of thought, Light is primary, heat is secondary. Or Fire is primary, heat is secondary, light is tertiary. Earth-gravity-inertia. Air-electricity-gravity (lack of). Why not have powder or dust as an element? Maybe as a secondary element of earth? I'm thinking I'm going to make one up for the long gaming weekend I'm hoping to have. I just have to modify some wording in the spells to make it work.