Rock mass fractures adversely affect the production of ornamental stone quarries. Fractures cause natural rock blocks, which threaten extraction of the required commercial block size of ornamental stones. Accurate subsurface detection and modeling of fractures are required for pre-exploitation evaluation and planning. This paper introduces a new three-dimensional deterministic fracture modeling approach using ground penetrating radar (GPR) as a data acquisition tool. A case study was performed in a fractured bench of a sandstone quarry in Firenzuola, Italy, using a 400 MHz GPR antenna. To accurately detect fractures at true depth, an in situ calibration based on previous knowledge of the depth of a subsurface reference reflector allowed us to estimate a bulk dielectric constant of the rock mass during the time of data acquisition. A data interpretation tracing technique was developed to model fractures as 3-D surfaces in two forms, either irregular or planes. The modeled fractures were visualized through a multi-platform visualization software package (ParaView). A comparison between the orientations of the fractures measured by the traditional manual method and the orientations of the modeled fractures is presented as a possible geologic validation for the detection and interpretation of fractures. For the objective of pre-exploitation evaluation, a distribution analysis provided an evaluation-based fracture index for the bench in the case study.