In my latest game I was shocked to discover that there was absolutely NO ALUMINUM anywhere on the map! In previous games, I experienced an unequal distribution of resources; in one I lacked Niter and Coal in my territory, and another I lacked Iron, Horses, and Uranium. But in my most recent game, there was no Aluminum anywhere on the map. I even checked what resources the AI civs had to trade, thinking that maybe there was a glitch and I couldn't see the Aluminum that existed on the map, but none of the AI civs (or city-states) had Aluminum either. This has to be a bug because it makes no sense why Firaxis would deliberately allow randomly created maps to be generated without a vital strategic resource.