The sparry magnesite deposit of Radenthein, operated by th Veitsch-Radex GmbH & Co of the RHI Group is situtated 10 km north of Radenthein/Carinthia Austria within the Austroalpine Crystalline Complex. Mining geological investigations were focussed to a rock mechanic rating (classification), a structural fabric (fault) analysis and a 3 D-modelling of the ore body. Because of favourable and unfavourable dip/strike directions of faults, planned heading and cross cut directions were optimized by the structural fabric(fault) analysis. A Rock mass classification was done for the initial estimate of the lining of the haulway Sohle 8 (level 8) and the planned ventilation pit as well as for the tendering of the ventilation pit. The methods of Hoek & Brown, Bieniawski, Laubscher and Barton were used. Rock classification is performed according to the homogeneous areas Sohle 7, Sohle 8 and ventilation pit for the magnesite and the host rocks for favourable and unfavourable areas. On the basis of the existing mine network, Bartons method has demonstrated the best fit to the geology. The purpose of the 3D model is the exploration of the boundaries of the deposit and a better definition of the resources.The construction of the model was done with the programs: Surpac Vision and AutoCad. The model 2004 is based on the model "Alt", new informations from lower levels of the pit and drillings at Sohle 7.