Dusts for Metallurgy's precious metals (zinc, platinum, silver) are not created by Ex Astris. Ex Nihilo produces these dusts, sands and gravels for platinum and silver if Thermal Expansion is installed so it makes sense that they were overlooked, but zinc is completely absent regardless.
Using just Metallurgy + Ex Nihilo + Ex Astris, both Platinum and Silver generate for me (http://puu.sh/gwUSD/13a5a7254f.jpg). I'll get onto adding Zinc shortly.
Dusts for Metallurgy's precious metals (zinc, platinum, silver) are not created by Ex Astris. Ex Nihilo produces these dusts, sands and gravels for platinum and silver if Thermal Expansion is installed so it makes sense that they were overlooked, but zinc is completely absent regardless.