blackcatatonic
Queen of Meme
About copper: I would like it more as a strategic resource used for spearmen, horsemen and such - but a lot more common than iron, and later on used for electric infrastructure (telephone/telegraph) lines.
Could also work like bonus resource that gives +20% production for classical era units, and with the discovery of electronics (or some other industrial/modern tech) a +3 gold bonus or something. Could also give +1 faith and/or culture with metal casting (should maybe a bonus belief thing)
It would be strange if it would be visible before Bronze working is discovered, but can a bonus resource be hidden and then revealed by a tech?
I could go with this. I was thinking +2 after Electricity or something.