I am a complete newbie so I apologize beforehand if my questions are stupid. I can't understand how exactly improvements work. According to the ingame wiki a hex with marble should give me one culture and I need to work it via a mine to get the bonus. However I get the culture even without the mine as long as I have a citizen working there, So the only purpose of a mine on such a resource is to get the amenity. Am I correct about that? IHowever I get bonus food if I build improvement on let's say wheat. And I wonder why these two hexes work in a different way. Correct me if I'm wrong but it seems to me that the bonus resources are added to the natural yields of each hex anyways and I get confused when do I get any extra resourse if I build improvement and when - not.