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Mount Arci is located in central-western Sardinia, inland from the Gulf of Oristano. It has an approximately elliptical shape, elongated in a north-south direction, with the major axis measuring about thirty kilometers and the minor axis around seven. The highest elevation is reached at 812 meters above sea level at the neck (an ancient volcanic conduit) of Trebina Longa.
The Geomineral Park of Mount Arci covers an area of about 270 square kilometers, equivalent to 7% of the total area included in the Geomineral Park of Sardinia.

The first mining district in Sardinia was established at the beginning of the 6th millennium BCE, when small communities, arriving on the island as part of Neolithic colonization, discovered and began using the obsidian of Mount Arci. This glassy rock, mostly black, with a shiny and conchoidal fracture of volcanic origin, was highly sought after by people of the "pre-metallurgical age" as a raw material for the production of weapons and tools.

Mount Arci, along with Palmarola, Lipari, and Pantelleria, was one of the rare extraction sites in the Mediterranean area. Today, ten collection centers, 72 processing sites located near the outcrops, and about 200 prehistoric stations are known. These are spread throughout Sardinia and are easily recognizable by the abundance of obsidian fragments and flakes, residues of the crafting process.

A thriving trade in what is referred to as the "black gold of antiquity" led to the establishment of collection centers and lithic workshops. From these, the material, either raw or already worked, was distributed not only across Sardinia but also to nearby Corsica, Tuscany, Liguria, and southern France—regions all lacking this valuable resource.