The obsidian mountain.
The peculiarity of Monte Arci is its abundance of obsidian, a black, vitreous rock of volcanic origin. Known as the "black gold of the Neolithic", obsidian was prized for its hardness and the ease with which it is fractured. It was used to make utensils and weapons, and was exported throughout the Mediterranean basin.
In Monte Arci's beautiful forest (cyclamens, crocuses, peonies, pancratium illiricum) and in the autumn there are mushrooms.
The mountain has many springs, among them, Acquafrida, Sennixeddu, Fustiobau and Mitza Mraxani which means the presence of an interesting variety of fauna: wild boars, foxes, wild cats, martens, and as for birds: jays, crows, woodpeckers, woodpigeons, hoopoes, buzzards and kestrels.
Because of its inaccessibility, the goshawk and, perhaps, some Bonelli eagles nest in the mountain. There are also many interesting archaeological site between Mitza Mraxani and Sa Domu de is Caumbus.