I've been wondering how far do mines mine? When I first started playing the game some 20 years ago whenever my geologists found some ore I used to place as many mines on top of it as I could but I noticed that the AI tended to use fewer mines and leave some empty space between them. How do I place my mines most efficiently to eventually get the same amount of ore but use fewer resources? I was not able to find this information online or in the manual.

This is the range of a mine - 3 dots radius from its center. (7 resources x 37 spots) = Maximum of 259 resources that can be mined by a mine.