With v1.2 there are several alternate ores available. With every world generation only one of each below 7 pairs will be available (i.e. if the world contains Tin then it will not contain Copper etc.) :-
Tin / Copper
Iron / Lead
Tungsten / Silver
Gold / Platinum
Palladium / Cobalt
Orichalcum / Mythril
Titanium / Adamantite
So my question is, do the ores spawn as a 'set' i.e. if the world contains Tin, would it also always contain Iron, Tungsten, Gold, Palladium ... etc.? Or does every ore type have a 50/50 chance to be one or the other?
Reason I ask is because I want to collect all armor types and I want to know roughly how many worlds I need to generate to find all the ore types (esp. hardmode ores)