Dimension stone industry, is now one of the world's most widely used by financial industry. Growth in using dimension stone in construction industry also shows the importance of this sector. Investment in this sector of the industry has always been associated with high risks. One of the most significant risks for investors in this industry is variety of natural discontinuities in the rock mass which affect the quality of exploited stones. Existence of discontinuities in dimensional stones, in addition to reducing the extraction efficiency of the quarries, reduces the safety factor and increases risks to human life.Quarry steps stability, strongly characterized by discontinuities properties such as dip, dip direction, strike, opening, extension, filling and spacing. o, it seems to be very logical and rational to do study, identify and analysis of discontinuities in the rock mass, prior to any exploitation activity in quarries.Usually this important issue would not be considered in dimensional stone quarries and realizing the importance of this matter can be followed by wasting huge costs in the inappropriate extractive strikes. However, optimization of extraction and increasing the efficiency can be result of doing a brief study around the discontinuities in the quarries. Since discontinuities often have irregular distribution and direction , dealing them with cutting lines can have a significant effect in reducing or increasing of fragmentation of rock blocks. Therefore this research is recommended to study, evaluate and analysis the discontinuities properties before start mining operations in order to achieve maximum extraction efficiency in dimensional stone quarries. In this thesis, by collecting discontinuities properties in Josheghan white marble quarry using scan line method and then using the 3DEC software for modeling jointed rock mass, and analysis of results of modeling, finally it was observed that cutting lines in the mine dealing with the direction of the dominant discontinuities in the region, have the angle of 13.44 degrees. So, if we change the direction of cutting lines the amount of 13.44 degrees to the East, finally, by comparing the tonnage and volume of non-recoverable stone blocks before and after changing direction, increasing efficiency of extraction, reducing the fragmentation of stone blocks and optimization of extraction can be observed
