In the front of the Monte Oladri quarry, rocks of volcanic origin from Monte Oladri, Su Pardu and Monte Zara can be observed. In addition to the volcanic component, Quaternary sediments representing partially cemented groundwater debris are detected developing in the hillside and at the base of the front. Several studies describe the succession of volcanites in the Monastir sector, indicating an age between the Upper Oligocene and the Lower Miocene.
Andesites of Mount Oladri
In the basal part of the front it is possible to observe rocks derived from andesitic lavas of different colorations depending on the degree of alteration of the rock.
Volcanoclastites of su Pardu
Above the andesites of Mount Oladri, a complex of volcano-sedimentary rocks of pyroclastic character (i.e., generated by volcanic material produced during an eruption and consisting of ash, lapilli, etc.) is found.
Andesites of Mount Zara
In the uppermost part of the succession visible in the front, other andesitic lavas with different coloration are found. Again, the rock has large crystals immersed in a background paste that is, however, more glassy than the previous one.
Quarry activities
Map documentation shows that mining of the aggregates surrounding the hills was started from 1962. At that time, the industrial area of Monastir had not yet been developed and the use of the surrounding areas was solely agricultural. In 1968, excavation activity was given a major boost. The quarry appeared to be articulated on two main steps, and the quarry itself appeared to be surrounded by a series of tracks that also connected the excavation area to existing infrastructure. The area of the mineral processing plant occupied the same location as today. Exploitation of the resource was still taking place in 1977, when the quarry took on a conformation more or less similar to the present one. It most likely ceased operations around the 1980s (from official data in 1982), after the construction of the Ussana and Monastir interchanges in the corresponding sections of the S.S. 131, and it is not ruled out that the materials used for construction came precisely from the Mozzarini quarry.
The quarry was cultivated with the use of explosives (almost up to the elevation of the overhanging Castle). Mining was particularly interested in high-strength andesite. The materials were destined both for infrastructure works on the 131 and for the port of Cagliari, where the extracted reef boulders (some of which can still be seen right on the quarry yard) were used in the construction of Cagliari’s port works.
