This topic has been discussed in dozens of threads. To simply put it, as I understand, your blacksmithing level (1-10) of the quality you can craft is the level of the nodes. So if your BS is 9/10 then I would assume you will find voidstone.
My smithing is maxed out, so I should get VR 15-16 mats. That's cool. I started a new Orc char last night to experience it from another perspective. Didn't want to be stuck with Iron forever. Thanks