Rockiness

The Rockiness of an area determines that region's Mineral production potential. Regions can be flat, rolling, or rocky. Flat regions produce no minerals unless a mine is build there, in which case they can produce one. Rolling regions produce a single mineral, which can be increased to two with a mine. Unimproved Rocky regions also produce 1, but can produce 4 with a mine and road. Rocky areas inhibit movement, costing twice the normal number of moves to enter. They also provide a modest defensive benefit in combat. Ocean squares produce minerals only if you build a mining platform, in which case they produce 2. Special Mineral Resource squares produce two additional minerals per turn, and can be increased to three extra with a mine. Crater squares also produce one extra mineral.