This paper presents the design and implementat.ion of a knowledge-based system, Queensland Mineral Deposit Expert (QMDE). The primary goal of this system is to assist in the modelling and economic assessment of potential mineral deposits in Queensland. The system produces ,an assessment of a mineral occurrence's affinity to standard deposits for which economic characteristics such as grade, current production tonnage, employment, and estimated mine value. These parameters are known from the mining operations t.hat, have occurred or currently are in progress at, these deposits. QMDE is developed using the VF'- expert system shell. The system is affordable, can be made easily available on most personal computers, and can be enhanced with minimum effort. It has been successfully implemented in the Queensland millera1 environment, and is currently being extended for specific commodity domains such as Gold and Copper. 'The system can be readily tailored to address specific mineral commodities and environment,s. The functions are being extended to incorporate intelligent access to large data bases of facts stored on Queensland's mineral deposit,s t.hrough manipulation of d a h models of mineral occurrence profiles and mining accident statistics.