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The worldwide development of studies concerning volcanic-related deposits caused renewed interest in epithermal mineralizations in Sardinia and a prospecting program was developed in the eighties. A series of field surveys showed that hydrothermal alteration halos are widespread in the Tertiary volcanic terrains, and Au-Ag bearing mineralized outcrops were detected in a few localities. An exploration program was performed which reached the ore evaluation stage in two areas. The first economically viable gold deposit discovered in the island is located in the Furtei area, it is associated with a high sulfidation gold-copper epithermal system. A group of mineralized bodies was also discovered at Osilo, northwestern Sardinia. The outcrops are hosted in Upper Oligocene to Lower Miocene volcanics, which occur as lava flows and domes. The ore zone minerals consist mainly of disseminated pyrite with lesser amounts of arsenopyrite, gold and silver are microscopically observed as fine grains of electrum in crustiform banded quartz. The size of the outcrops make the development of their exploration a matter of high interest but go-ahead for this program cannot be given until all legal matters over permitting are resolved because exploration drilling encountered an artesian subterranean water and additional drilling within the area is considered not advisable.

This paper presents a detailed petrochemical and minerochemical study on some Roman granite columns from the archaeological site of Uthina. An ancient roman city located about 30km SW from Tunis (Tunisia), near the village of Oudhna. Some of the sampled columns show a very similar macroscopic aspect to the pinkish-grey granites outcropping in the ancient quarry area of Capo Testa, in northern Sardinia (Italy). In order to provide a comparison between the archaeological samples and the granite of these quarries a detailed geo-archeological survey and sampling of the Capicciolu, Li Petri Taddati, Cala Romana, Cava Grande del Torre "loci" (Capo Testa peninsula) and of the two La Marmorata Island "loci" were carried out. The results of the analyses showed that three of the sampled columns (these pinkish-grey in colour) have a strong resemblance with the samples of La Marmorata quarries. This demonstrates that, during the II-III centuries AD, the granite of North Sardinia quarries had a diffusion beyond the regional limits, confirming the identification of several granite artifacts discovered in monuments of the ancient Rome and in some other cities of the North Africa provinces.

The Lake Flumendosa is one of the main basins of an hydraulic system of artificial lakes that is the major water resource for southern Sardinia. It is situated in ore-rich terrains which are responsible for the supply of different heavy metals in the bottom sediments forming in this lake. The chemical and mineralogical composition of these materials reflects the lithology of the country rocks and is strongly influenced by the surrounding ore mineral occurrences. At many locations mining has been active for several decades affecting not only important ore bodies, but also minor occurrences and mineralised outcrops so that mining excavations, trenches, galleries and exploitations gave origin to numerous dumps which, along with the unexplored mineralised outcrops, supply metals to the lake sediments. In recent years the fluxes of many trace elements from terrestrial or atmospheric sources to the aquatic environment of these reservoirs has increased either as a direct action of mining and other industrial operations or as an indirect consequence owing to acidification of the rains. Although the period of most intense sulphide oxidation and associated release of dissolved metals has passed the transports of contaminants through underlying aquifers will continue. Furthermore, because of the semiarid climate of this island, along with the uneven distributions of rains, water levels in this lakes are prone to broad yearly variations and consequently their sediments are periodically prone to the action of the meteoric waters and of the atmosphere which causes oxidation and remobilisation of most metals. However the metal-rich sediments of the lake appear at present sufficiently stable as elemental concentrations in the water reaching the treatment plants are normally below the permissible limits for drinking use. Metals reprecipitate in less soluble forms and accumulate in the deepest parts of the sedimentary piles which would act as a trap for the metals. Data on metal contents in the sediments are examined, as well as deriving pollution risks. Distribution maps have been drawn for each element to assist in the assessment of the dispersion and accumulation effects. The mapping, together with statistical treatment of the results and comparison with previous data has allowed hypotheses to be advanced about the origin and fate of the various pollutants.

The metallogenic periods took place at different moments of the geological evolution of Sardinia, but at places they interacted: the close correlation between the metal parageneses in the Ordovician - Silurian sequences outcropping in the central part of the island, and the veins and masses associated with the Hercynian magmatism is depicted. The volcanic-sedimentary mixed-sulphide lenses contained in Silurian occurrences show clear sedimetary structures, and the connection with coeval volcanics seems evident. These mineralizations are thought to be the protores for the subsequent hercynian orogenesis which had a strong effect as a promoter of the remoulding of preexisting mineral concentrations to give new ore and industrial minerals. A new prospecting programme has been started in Central Sardinia following the ore-bearing horizon along the Ordovician-Silurian boundary with the purpose to better understand these primary metal depositions, their relationship with geodynamic structures, and ore mobilisations caused by the Hercynian granites. The geochemical anomalies of this horizon detected in the area of "Castello Medusa " support detailed prospecting works.

The satellite based GPS tool needs a clear view of sky for determining a geodetic position and hence it is particularly suitable in overall projects of open-pit recovery and landscape restoration. The purpose of such measurements is to make highly accurate topographical maps thus forming the backbone of a project. In the work presented here geodetic measurements are combined with advanced visualization techniques and GIS applications in a possible recovery plan of the abandoned excavations of Bonucoro in the mining district of Orani, central Sardinia. On the base of the naturalistic and geographical contexts of the mining area and its surroundings, a few proposals concerning the re-utilisation of these excavations are here presented. The preparatory work consisted in the characterisation of the area under study through a topographic survey then a geodetic control network was established by the use of GPS technique to describe the morphologic features of the landscape and for the subsequent three dimensional analysis and geoprocessing by commercial GIS/CAD software. The final step is represented by the use of VUEInfinite that is capable to integrate graphical data with geological and morphological attributes enabling the creation of virtual 3D environments thus giving an imagination of a present, past or future landscape development also allowing for visual impact assessments.

In the district of Orani, central Sardinia, several talc-chlorite-feldspar bodies, hosted in Palaeozoic metamorphics and granites, have long been mined by open- pit operations. The mining activity has deeply modified the original landscape of the Lasasai-Bonucoro area. Thus the rearrangement of this area, in particular of the open-pit works that are now occupied by newly formed pools, filled with water from aquifers flowing along faults crossed by mining operations, should be considered as an overall project of landscape restoration. In the first phase of this work, the environmental and hydrogeological characterisation and the general definition of different zones characterised by different sets of intervention operations has already been made. The following step will include the detailed definition of the different technological interventions to be performed. In order to attain a rehabilitation of this area, first of all the interventions will include: 1)smoothing and re-modelling of local morphology in its still rough sites, namely a few points of the mine benches and dumps, by removing the volumes in excess and settling them again in the hollows, on the base of the indications obtained from opportunely plotted sections; 2) restoration of the removed soil covers, and rehabilitation of the newly formed surfaces after waste disposal, trough re-vegetation techniques including settlement of vegetal soil and nutrients, herbaceous essence hydro-sowing, temporary automatic sprinkling; 3) rehabilitation of the corrected slopes, and in general of the remaining poorly vegetated surfaces, trough the above re-vegetation techniques. The above operations will result in a slightly modified plane-altimetrical and landscape arrangement. However these interventions will be sufficient to reach a new environmental qualification, characterised by several opportunities of exploitation. Particular conditions, such as the constant outflow of good-quality water and the amenity of the surrounding countryside, are favourable to an easy accomplishment of the above suggestions and perhaps of other ones. Thus the possible utilisation of the resources of Lasasai-Bonucoro at least includes the following opportunities, which do not exclude each other: 1) solace locality; 2) mineral water bottling. In this way, the environmental recovery of Lasasai-Bonucoro will lead to new social-economic, cultural, recreational, and touristy opportunities.

Prospecting in the northern part of Sardinia, within a N-S-trending tectonic trough has led to the discovery of a number of mineralized sections in the bottom terrigenous sediments that were produced during a Miocene marine transgression. The mineralization occurs at the contact between pyroclastics and clastic sediments and consists of authigenic oxides and sulphides, suggesting fluctuations of redox conditions in a near-shore, high-pH environment. Evidence indicates that metals were transported under warm and semi-arid climatic conditions by ground waters and deposited in environments characterized by high pH and fluctuating Eh conditions. Evidence also suggests that mineralization occurred during diagenesis.

The paper deals with a project developed to lead the application of pulsating jet technology for ornamental stone surface finishing from a research phase to an industrial level. The project is based on the financial support of the Regional Government of Sardinia – Italy and on the contributes of some Sardinian companies interested in the industrial developments.