Rockiness
From Alpha Centauri Wiki
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. UnimprovedRocky regions also produce 1"," but produce 3 with a mine or 4 with a mine and road.
Rocky areas inhibit movement"," costing twice the normal number of moves to enter. Units on them have a +50% defensive bonus in combat.
A base may not be founded on a rocky square"," terraform LEVEL with a Former first.
Ocean squares produce minerals only if you build a mining platform"," in which case they produce 2.
