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ca <br />,,: <br />• MainCressonSlopeEvaluation AdrianBrown <br />5.3 Starter Mine <br />The initial excavation at the Main Cresson Mine was in the center of the orebody, just south of the north <br />mine, and just north of the south mine. This "Starter Mine" is now largely mined out, but provided early <br />and valuable insight into the structural fabric of the entire Cresson Orebody. The information obtained <br />from this mine is presented below, to provide a record of this data. <br />5.3.1 Joint Sets <br />The joints measured in the Starter Mine are presented as a polar equal area stereonet on Figure 9; the <br />contoured polaz density is presented in Figure 10. As can be seen from the figures, this mine has a single <br />main vertical joint set, and a smaller horizontal set: <br />1. Dip direction 60°/80° dip (NNW-SSE strike, 80° dip to the ENE). This joint set is the only <br />significantly identifiable joint/fault system in the Starter Mine. The set has dominantly vertical <br />joints, striking west of north. Faulting is also along the same direction, as shown in Figure 11. <br />2. Dip direction 0°/10° dip (East-West strike, 10° dip to the north). This minor joint set is <br />essentially horizontal. There are relatively few joints of this orientation, when compared with <br />the major joint set. <br />• In the starter mine, it is possible to follow individual joint systems through a number of benches, such that <br />the horizontal continuity of many of the joints in the principle set present appears to be considerable, at <br />least in the order of 500 feet in some cases. <br />5.3.2 Fracture Intensity <br />Fracture intensity observed in the starter mine is moderate; with typical joint spacing in the order of 1-3 <br />feet. <br />5.3.3 Structural Stability <br />The structural stability of the wall has been evaluated in Figure 11, far the west wall of the Starter Mine <br />area. This shows the polaz domains in which structural failure could occur overlain on the structural <br />information, by type. The structural failure conditions are: . <br />1. Sliding Failure. Large scale sliding failure is unlikely in azeas with this structural fabric. There <br />are few observed fractures which have the potential to create a sliding failure on this wall. No <br />such failures have been observed to occur, although the wall was only approximately 200 feet <br />high at its highest. <br />2. Toppling Failure. There are no structural surfaces which provide the opportunity for toppling <br />failure or movement on this wall. <br />Overall, the performance of this mine has been good,~with some post-mining raveling on the north face, <br />• and along the principal fault zone which runs from the north-west to the south-east corners of the mine. <br />No overall instability has been observed. <br />1385D.980612 23 <br />