Altars will only spawn either of the 3 tiers.
cobalt OR palladium
mythril OR orichalc
adamantite OR titanium
you can aquire the others from crates too though (but that's quite tedious, and RNG dependant)
by the way, you can craft a hardmode anvil either from mytril or orichalc, and a hardmode forge either from adamantite or titanium (show the ore to the guide for the recipe, it does requires the ore for the forge, not bars (since you can't craft bars without the forge)
on a side note... since every smashed altar has 1/3 chance to turn a single, random corruptible block underground corrupted/crimsoned or hallowed, which will then spread (and fast in early hardmode)... if you indeed smashed tons of altars, that situation could turn really uggly really soon...