I think that's should not be a discusson about the material of the hammer. I guess it's just about how rare a ressource is to find or how difficult to achieve. Since there will be lot of more details which will be far from logical things, I REALLY don't care xD I wonder why there are more complainings about gold then all the ruby, diamant, saphire, etc. hammers
But a few additional ores could by the way be:
tin (and together with copper you can creat bronze)
palladium, platinum etc.
Maybe this table of rarity of elements on earth can give a few more options and the way you COULD sort it:
Anyway I like the design! Great job here.
Especially that kind of lightning hammer (second of special).
God, it makes me think the miners will be the THORs of the game and smash with there lightning through the mountain! xD
I bet the design when smashing will look gorgeous. Will a hit electrify the element it hits?
Anyway super cool design!