Abstarct: The block caving mining method allows mining of massive, low grade deposits at depth, and has the lowest production costs and the highest production rates of any underground mining method is used today. Among the most important factors in block cave mines are fragmentation and caveability. Poor estimation of both of these variables can lead to production and processing problems, or in the worst scenario, failure of the project. Fragmentation in block caving method s has three stages. In situ, primary and secondary. In situ fragmentation is result of discontinuities with zero tension strength but primary and secondary fragmentations are happened in a rock blocks that seem intact and without any discontinuity. In reality in these blocks when induced stresses due to under cutting or shock and stress due to transition of rock mass are affected blocks, weak surfaces like, veinlet and schistose surfaces (surfaces with tension strength) are first candidates for breakage and slice. Target is construction a way for prediction of potential discontinuities. In next step baxsed on necessary energy for breakage, potential discontinuities are classified. We try to design and construct a new method for quantifying and classifying discontinuities in rock mass. This method helps us to have an initial estimate of fragmentation when induced stress and large scale displacement affect rock blocks. Veinlet and weak surfaces in rock like as schistose surfaces (surfaces with tension strength) are potential discontinuity. According to this test, potential discontinuities are classified to No 1, 2 and 3. In recent researches from different cave mining in the world, P32 (volumetric fracture intensity) is recognized the most effective parameter for cavability and fragmentation. Therefore performance of P32 for caving prefeasibility or feasibility in a Kahang Copper mine is checked. In this step a computer code written in Mathematica software baxsed on image processing method. With using this Digital Core Image processing code (DCP) RQD and P10 (lining joint intensity) are estimated very well. Basic advantages of this code are speed and accuracy processing. With these advantages, an operator can give necessary logs from core boxes, images without any difficulty for transportation of boxes, taking time and extra outgoing. In the next step P10 is estimated for 3D block models with geostatistic modeling way. Finally P32 is calculated from P10 with using of transportation coefficient for different levels. Fracture spacing, persistence and dispersion are more effective factors in cavability. In fact persistence of discontinuities especially in rock mass fractures, are finite. This has a high effect on cavability of rock mass in caving methods like in mass mining. In some of geometric modeling methods, like discrete fracture networks (DFN), discontinuities are finite and limit that have a good match with reality especially for cavability analysis. Mathematica Software is selected for writing 2dimensional discrete fracture network code (CAV-DFN2D), because of its good graphic and calculation abilities. CAV-DFN2D has good different abilities like producing of numerical and graphical outputs, making finite and infinite joints models, defining of complete blocks with computation of their areas from joints intersections, consideration of joints hierarchies, production of suitable outputs for numerical codes like UDEC & PFC2D and statistics outputs of any model geometrical parameters. geometrical modeling is constracted for joints geometrical information from site surveying of Kahang mine. After determination of Representative Elementary Volume (15×15 m2) and verifying of model, complete blocks with their areas are determined. Results are shown about 30% of blocks are infinite or big and this is a challenge for primary and secondary fragmentations. In next step potential joints are modeled with CAV-DFN2D. To estimate the primary and secondary fragmentation a code was wrote with Mathematica (PSF). In this program the primary and secondary fragmentation during caving process is estimated baxsed on the criteria defined in the thesis and assuming that the separation is only on weak surface. After analyzing with existing assumptions, draw column height of 150 meters with an active width of 30 meters, to achieve an appropriate fragmentation, is considered a good value.