Iron is not bad and you can use it in mountains, but silver is better. If you have surplus of silver, i say go for it.
And for pickaxes and golems… hmmm it’s like an urban legend. It does yellow dmg, meaning it’s super effective. But as Scrumpy said, use mace. It’s easier and you can use shield with it to parry for higher dmg. With decent clubs skill points you can kill golems with 3 middle click heavy attacks. I even managed to 2 hit kill a stone golem but my clubs skill was in 70’s and I was using porcupine which does a slightly higher dmg than iron mace