## 3 Discussion  
Taking into account the results obtained from XRD, calcite was the predominant component, even though more than 20% of the marble was made up of other elements. The presence of quartz cannot be neglected, with a percentage of 11.2%. The presence of impurities also strongly influenced the campaign of the microhardness tests. In fact, the results achieved confirmed relatively high microhardness values when compared with the range of marble, typically from 1500 MPa to 3000 MPa [50]. Considering the upper limit of the range, the hardness was below 3000 MPa for 40%, 50%, and 40% of the cumulative curves for samples one, two, and four, respectively. In contrast, in sample three, only 8% of the determinations gave a hardness greater than 3000 MPa. This result was expected: in fact, sample three was characterized by only a tiny vein of grey intrusion. However, the microhardness results justify the company's choice of tool material. The choice to discard tungsten carbide tools in the chainsaw was correct, since the microhardness values of this compound ranged between 10,000 MPa and 14,000 MPa, values that were often exceeded during testing. Consequently, the company's choice to use polycrystalline diamond tools can be considered correct, since this material is characterized by a Vickers hardness of about 55,000 MPa [51].  
As for the CAI test campaign, the studied marble was recognized as an average abrasive material, the average CAI value being equal to 2.77. This result highlighted the abrasive potential of the impurities present in the marble and previously recognized by XRD; in fact, the CAI was higher than that of pure marble (between 0.60 and 1.00, as suggested by the Colorado School of Mines). In particular, the sample which had areas where the CAI was higher than 3 could be due to the presence of flinty marble (signifying a highly abrasive material).  
Regarding the wear, it should be remarked that tool wear is determined by complex laws [52]. Pettaining to the test performed using the SATA, the tested sample was characterized by a wear bell with a peak at 5% water content. From the results, it was confirmed that the water content deeply affected the weight loss of the test disk, as discussed by the authors of [41; 42; 46]. Starting from a soil moisture percentage equal to the natural condition (1%), increasing the water content did not provide a beneficial effect until a percentage of 5% was reached. After this value, a further increase in water content resulted in a decrease in weight loss. However, comparing the wear bell of marble with that of quartzite, it was evident that the wear potential was similar, the peaks being of the same  
Figure 12: Marble wear bell and wear conditioning tests (4% and 9% moisture content).  
order of magnitude (close to 0.6 g). The wear tests with conditioning agents revealed interesting aspects, namely that the additives need a certain dosage to work properly. Tests carried out with Products A and B in solution, dosed and added to the marble sample to achieve 4% moister content, showed no reduction in weight loss, while tests performed with a conditioning agent capable of achieving 9% moisture content provided a reduction in weight loss of 50%. It can be stated that a reduction in the wear was observed when the additive used surpassed a certain threshold. The mechanism of wear reduction is certainly a function of the amount of the additive (9% moisture content provides the lowest wear). Anyway, it should be noticed that additives, in order to work properly, need to be conveyed homogeneously in the conditioned soils. In conclusion, it can be hypothesized that there exists a critical moisture content, recognizable in this case as between 4% and 9%, which, once reached, allows the added product to properly exert its anti-wear action.