User blog comment:Unownshipper/Metallurgists Wanted: Rapture's Natural Resources/@comment-3967731-20140811034544

Here's another valuable substance: monel.

Monel metal is stronger and less prone to corosion than even stainless steal and it's primary components are nickel and copper. This makes it more expensive than your average building materials, but what does Rapture have in abundance? Nickel and copper, which are volcanic minerals.