The basement contact zone, a major fault structure underlying the copper orebodies at Mount Isa, has a significant influence on orebody extraction._x000D_
The zone is comprised of a variety of weak, barren lithologies which often create very difficult mining conditions, contribute to stope dilution, and have an adverse effect on concentrator recoveries._x000D_
The geological characteristics of the contact zone are described, and the importance of timely, accurate geological information emphasized._x000D_
A variety of mine design strategies have been employed to reduce the impact of the contact zone on orebody extraction. Some of these are discussed, together with current trends in the southern areas where orebody geometry and hence mining methods change markedly._x000D_
Recent developments in ground support techniques, such as cable dowel reinforcement, have significantly improved ground conditions in the contact zone. An example of the methods employed to improve knowledge of ground behaviour is presented. The trend towards increasing automation and larger equipment requires larger excavations; consequently ground support practices and knowledge of ground behaviour must continue to advance. Rock mechanics investigations will remain an essential part of the mine design process.