No - they are random. Gold one is ultra rare drop. It took me like forever to get enough for ally and for 1 mystic kin. ( 10 ffor ally and 30 gold for building) - but I have both...it just drops ultra rarely. If you think filling some outrageous quest with really insane asks ( like 70 golden nuggets) will give you better chances -NO, just as likely to get bronze. So skip those - always check what they are asking. Elves are sneaky and sometimes they ask really rare items - and quite a lot- I've been asked like 70 mithril, golden nuggets, eels - those are nightmare to get if you need those... so always check what they want - giving them better items does NOT increase your chances of getting gold. Just be patient -eventually you will get there.