Low and high sulphidation epithermal gold deposits in Sardinia, Italy

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.