On display are thousands of minerals and fossils on which the geological evolution of the island and specifically of Marmilla is written, with a complex history spanning from around 20 million to about two million years ago. Set up in the premises of the former convent of the Capuchin Fathers, a monumental monastery from the mid-17th century - to which is attached the church of San Francesco - the Geomuseum of Monte Arci in Masullas is a one-of-a-kind in Sardinia, arising from the patient work of Vincenzo Incani in collecting and cataloguing, resulting in the mineralogical and paleontological collections. To be admired are specimens of stones with fossils of ancient marine animals, dioramas that reflect the volcanic activities and various minerals, in particular colourful jasper (rocks from the marine environment), formed during the eruptions of the 'old volcano' of Monte Arci. In the ‘sala flù’, you will be dazzled by spectacular minerals with fluorescent colours.