So far, I've gotten a single ingot out of 130 chunks of adamantine.
When it's been stated that the chance of getting one is 5% aka. 1 in 20.
I think the risk and effort vs. reward of this should be looked at.
A 30.5 lbs. 4 slot item to have a minuscule chance of getting an ingot of something that doesn't even offer much more than enchanting potential.
I propose that they either be made lighter, smaller or increase the chance of adamantine. Perhaps a bit of both.