Mineralogical and compositional evidence of a district- scale Sn-W skarn system in SW Sardinia: a review

We studied three representative skarn orebodies of SW Sardinia (Perda Niedda, Monte Tamara and Rosas), related to ilmenite-series ferroan granites to assess their Sn-W and other Critical Raw Materials (CRM) metallogenic potential. The Perda Niedda skarn hosts magnetite, fluorite, cassiterite and minor sulfides in a garnet- (clinopyroxene)-amphibole-chlorite association at contact with granites. At Monte Tamara, scheelite-bearing hydrothermal veins and clinopyroxene-garnet skarns occur with minor cassiterite-stannite-molybdenite and Bisulfosalts. Base-metal sulfides with subordinate magnetite-cassiterite-fluorite veinlets prevail at Rosas. Clinopyroxene, garnet and epidote mineral chemistry from the three locations allows a detailed reconstruction of the mineralised systems, in terms of proximity to causative intrusion, compositional variations of ores and Sn-W and CRM enrichment. Overall, the highlighted common features of the three skarns indicate that they may be framed within a single, district-scale Sn-W skarn system. Overall, their different mineralogy and geochemical fingerprint reflect formation mechanisms controlled by their distance from the causative intrusion.