Board Thread:General Discussion/@comment-24.247.108.45-20130607213225/@comment-73.10.62.120-20160523002702

Speaking as a professional chemist:

The carbon used to make steel actually comes from CHARCOAL ASH. This could be from the very fires used for the smelter. So you don't need an external carbon source, and really "carbon ore" would translate as either coal, graphite, or diamond depending how tightly the molecules are bound into a crystal structure. So I think this particular in-game mineral is not meant to be carbon, though it might have some small percentage of carbon in it.

Corundum probably would represent (in real life) some mineral mixture of nickel, magnesium, manganese, chromium, and/or aluminum... not actually a "pure" mineral itself. So think something along the lines of mica or shale. Just a bunch of clay mixed with low levels of other metals to "dope" the steel and make it stronger than just regular sheet metal. Probably, just based on how it is used to convert iron into steel.