Thanks for the suggestions!
Zinc is on my backburner list. The challenge with zinc in the "vanilla+" setting is that two of it's major uses are in alloys and as an intermediate to other intermediates. These two use cases don't fold well into vanilla. But I'll definitely keep thinking on it
I'll consider oil/tar sands resources. I haven't really thought too much on hydrocarbons in general, yet. Pyanodons Coal Processing and Petroleum Handling sort of show how complex they quickly become. I'll try to think about a satisfying way to do it in the "vanilla+" style.
