• Crystal Size Distribution
• annealing
• Schwartz-Saltykov

Abstract.
The structural use of marble requires mechanical and environmental endurance. Parameters that describe these characteristics are obtained with expensive and long tests that require special laboratories and equipments. In this thesis I describe how to use optical properties of calcite to obtain crystalline textures of marbles, in order to achieve a user-friendly and cheap method of general use (laboratories, sawmills, quarries). Quantitative determinations (Crystal Size Distributions - CSD) of rock textures have been tentatively correlated with mechanical and physical parameters of resistance. This research began surveying few images on a limited surface of a sample. Images are then processed and assembled using appropriate programs and developing special algorithm. After obtaining CSD, samples were tested following standard procedures evidencing correlations. The initial tests were performed using a paper scanner and processing four images of the same planar surface of a rock each rotated of 90°. Reassembling images was not possible, due to images distortions caused by the features of the scanner. Following attempts were addressed to completely static system, made up of a support holding up a camera and an appropriate lighting equipment, coaxial with camera, remote controlled. I this way we have photographed the surfaces of “verso”, “verso secondo” and “contro “ of 20 samples, of Apuan Apls marbles. We have obtained enough photos to cover all the surface. Together with the development of surveying system we have developed processing algorithm on the ImageJ platform. With macro PANOPTEStanti we have processed images obtaining quantitative data on crystalline textures , then processed to get CSD with Schwartz-Saltykov method. CSD diagrams highlight that the absolutely prevalent mechanism of development of crystal is annealing. In second place, the almost rectilinear pattern of CSD diagrams in semi-logarithmic scale, demonstrates that the ratio between the number of crystals of two adjacent classes is constant. Thus it is possible to derive a mathematic relation for the annealing in Apuan marbles. The third consideration is that stereological reconstruction provides evidence of a mean grain size larger than found in literature. The results of this research are furthermore applicable, with suitable adjustments, also to other materials like composites and ceramics used at high temperatures.