Document Type : Case Study


1 Geology Department, Faculty of Basic Science, Payame Noor University (PNU), Tehran, Iran

2 Geology Department, Faculty of Basic Science, Birjand University, Birjand, Iran



One of the significant negative factors involved in exploiting granite stones as ornamental stones is the presence of heterogeneous fractures within the rock mass. Joints can either be destructive or beneficial in the production granite piles and building stone mines depending on their characteristics. This work focuses on evaluating the joints in the Divchal mine area of Kelardasht, north Iran. To get to that point, the main faults are surveyed from the aerial photograph, geological and tectonic maps, and field observations. According to this implementation, a density map of faults is provided for the entire studied area. The characteristics of the main joints including the length, slope, number, and orientation are collected in the mine area. The volumetric percentage of joints ( ) and joint set spacing ( ) parameters are computed at specific stations to identify suitable locations for granite extraction. The findings of this work suggest that the lower the value of  (  < 10), the larger the blocks can be extracted. On the other hand, at the high  values, the width of the extraction block increases. These conditions are typically found in locations far from the main faults where the density of joints is low, and as a result, the distance between joints is higher. The values  > 60 indicate a crushed rock mass, and are typically observed in clay-free shear zones. It is recommended that the opening of the working face be avoided in situations near the main faults due to the fragmentation of rocks and denser joint spacing.