## 4 Results and Discussion
### XRD Analysis
The smaller peaks identified at 20 values around 20.8\({}^{\circ}\), 26.6\({}^{\circ}\), and 68\({}^{\circ}\) and the intensity of these reflections indicates that quartz is a secondary phase; however, its identification contributes to the mineralogical composition of the \"Comiso\" stone. The sharpness of the calcite and quartz peaks indicates a well-crystallized structure, suggesting that the minerals within the sample have undergone minimal weathering or alteration, preserving their crystalline integrity. The combination of calcite and quartz in the sample is coherent with the typical mineralogical composition of limestones, particularly those from the Comiso area, which are often characterized by high calcite content with minor siliceous impurities. This composition enhances the stone's workability and esthetic appeal, making it highly desirable for architectural uses [54]. The purity of the specimen is notable, as no other significant crystalline phases were detected. This supports the conclusion that the \"Comiso\" stone is primarily composed of calcite with a small but notable quartz content. Such a composition has been documented in studies focusing on the properties of Comiso limestone, confirming its suitability for both structural and decorative purposes [54]. The XRD analysis confirms that the mineralogical composition of this sample is mainly calcite, with quartz identified as a secondary phase. The well-crystallized structure and the lack of other mineral phases indicate its high purity, which makes it suitable for a variety of construction and ornamentation applications due to its beneficial mineralogical and mechanical properties [53]. Finally, the most representative XRD spectrum for the \"Mendicino\" stone is shown in Figure 5.  
Figure 4: XRD pattern of Comiso specimen, with prominent peaks attributed to calcite (Clt) and quartz (Qtz). The XRD analysis reveals a complex mineral composition with several distinct crystalline phases. The most prominent peaks correspond to dolomite, calcite, quartz, and aragonite. Dolomite is one of the most significant components, as indicated by the high-intensity peaks near 30\({}^{\circ}\) and 65\({}^{\circ}\) 20. This suggests that dolomite is the most abundant mineral in the stone, contributing to its structural characteristics. The presence of calcite is also notable, with peaks around 23\({}^{\circ}\), 29\({}^{\circ}\), and 47\({}^{\circ}\), signifying its role as a key carbonate mineral in the sample. Calcite often coexists with dolomite in sedimentary rocks, further confirming the geological origin of the stone. The diffraction peaks of quartz, a silicate mineral, are shown at 26.7\({}^{\circ}\) and 50\({}^{\circ}\), with minor intensity compared to the carbonate minerals. Quartz's presence can be attributed to its durability and widespread occurrence in natural stone formations, where it provides hardness and resilience. Aragonite, a polymorph of calcium carbonate, is identified with lower intensity peaks around 26\({}^{\circ}\) and 45\({}^{\circ}\), suggesting it is present in smaller quantities. Its formation could be related to diagenetic processes that occurred during the stone's geological history, possibly impacted by regional climatic factors including pressure and temperature. The combination of these minerals points to a sedimentary origin for the Mendicino stone, likely formed through processes of compaction and the recrystallization of carbonate-rich sediments [25]. The prevalence of dolomite and calcite, both common in limestones and dolostones, further supports this hypothesis. Additionally, the presence of quartz suggests that siliciclastic material was incorporated during the stone's formation, enhancing its mechanical properties. These results are consistent with findings from similar studies on carbonate stones [55]. The coexistence of dolomite and calcite in natural stones is a common feature of many geological formations, particularly those originating from marine environments where carbonate deposition is prevalent.