User blog comment:Unownshipper/Metallurgists Wanted: Rapture's Natural Resources/@comment-3967731-20140812061641

Concrete...it always seems to come back to concrete in this discussion. So why can't Rapture make its own? The basic building blocks appear to be water, sand, rocks, and cement.

According to an article I read:

"Cement is manufactured through a closely controlled chemical combination of calcium, silicon, aluminum, iron and other ingredients."

"Common materials used to manufacture cement include limestone, shells, and chalk or marl combined with shale, clay, slate, blast furnace slag, silica sand, and iron ore."

So what's the problem? Don't they have most (if not all) of the stuff in close proximity? Iron and aluminum we've got from hematite and bauxite from the volcano. Silicon comes from sand. Calcium is usually in sedimentary rocks, but can also occurr in igneous ones.