## 3 Results
### Raman Spectroscopy
The abundance of antigorite related to the foliated structure of the rock supports the classification of R4 as a serpentine schist, deriving from the metamorphism of a protolith containing calcium carbonate, which is testified by the presence of calcite in the rock. Geographical Individuation of Potential Primary and Secondary Sourcing Areas  
Throughout the Italian peninsula, five main areas have been selected in the research of the primary and secondary sourcing areas of the lithologies that constitute the samples: the Central Eastern Alps (Retiche Alps and Austrian Alps), the Western Alps, the northern sector of Apennines, the Calabrian Apennines, and the Islands (Nebrodi Mounts, Gennargentu Massif, and the north-eastern portion of Corsica Island). In detail, calcschist frequently associated with greenstone, is highlighted in the Western Alps, from the Maritime to the Pennine Alps, and in the northern Apennines, especially in the Voltri Group and in the External Ligurian Units areas. Metabasite outcrops are situated in the Graie and Cozie Alps sectors, then small outcrops are detected in the south-western portion of the Voltri Group, in the northern sector of the Calabrian Apennine and the Aspromonte massif. Calcschist associated with metabasite is also observed in the Sila Massif plateau and the Gennargentu Massif (Sardinia). In northern Italy, amphibolite and intrusive magmatic rocks, like diorite or gabbro, mainly outcrop in the Pennine Prealps, between Biella and Ivrea, and in the Lepontine Alps. Furthermore, gabbro can be found in the Ligurian Voltri Group area and associated with calcschist outcrops in the External Ligurian Units. Limited outcrops of amphibolite with greenstone are detected in the Maritime Alps, near the Argentera Mount (3.297 m a.s.l.) while amphibolite in much more extended outcrops is situated in Sicily, by the Nebrodi Mounts, and in the Sila Massif plateau as in the Aspromonte Massif. Granulite is found in limited locations within the Pennine and Lepontine Alps while more extended outcrops are in the Sila Massif plateau. Serpentinite is widespread in the Western Alps, in the area enclosed between the Monviso Massif and Mount Cervino, whereas a large outcrop can be found in the Voltri Group between Savona and Genoa. There is serpentinite with greenstone in the Nure Valley and on the right slope of the Trebbia Valley, between the towns of Travo and Bobbio. The study of secondary sourcing areas is carried out with a precise focus on northern Italy, as shown in Figure 11. The main watercourses and their minor tributaries can be considered secondary sources of rock in the form of cobbles and pebbles. The Po river and especially its minor affluents are highlighted because they directly intersect the geological outcrops and become the fragments' catchment area of the lithologies mentioned above. In detail, the calcschist with greenstone, metabasite, and serpentinite outcrops situated in the Cozie Alps may be transported from the Monviso Massif and the surrounding area by a network of torrents flowing into the Po and Dora Riparia rivers; some tributaries are Rio Bule, Rio dell'Alpetto, Grana torrent, Variata torrent, Variata of Chianale and Variata of Bellino torrents, and Pellice torrent. From the Graie Alps, calcschist and metabasite may travel from the Orco Valley with its Ribordone tributary, the Malone Valley, the Stura di Lanzo, and the Dora Riparia River basins, whereas from the upper Graie Alps, serpentinite, amphibite, and granulite may be carried by the Dora Baltea River basin, thanks to the catchment action of Marmore, Clavalite, Evancon, and Lys torrents. From the Pennine Alps, gabbro and diorite with amphibolite and granulite might be collected by the Sesia and Toce River hydrographic basins. Calcschist and amphibolite cobbles from the Maritime Alps may be respectively carried by the Rio Nero and the Rio Di Valle streams, flowing into the Bormida of Millesimo river and by the Gesso torrent belonging to the Stura di Demonte hydrographic basin.