How it began
Copper was mined in antiquity near Akjoujt in the Inchiri region of west-central Mauritania. The best-known site is the Grotte aux Chauves-souris, a mining cave at Guelb Moghrein excavated by Lambert and published in 1975. Radiocarbon dates from it calibrate to between 1378 and 203 BCE. The French and Mauritanian CUPRUM project reports slag deposits in the region with dates as early as 4500 years before present and notes copper may have been worked earlier still.
How it works
Miners followed copper ore into the hillside, leaving a worked cave. The ore was smelted nearby, leaving slag deposits. Analysis shows the metal was nearly pure copper with 2 to 3 percent arsenic, a signature that lets researchers recognize Akjoujt copper elsewhere. A 2025 study added tin, nickel, cobalt and lead isotope measurements to this chemical profile.
How it spread
Objects made of Akjoujt copper traveled far. The 2025 study identified three copper objects from the 1999 excavations at Walaldé as likely made from Akjoujt metal and dated to the later 1st millennium BCE. Other objects at the same site came from several regions across the Sahara, showing that copper moved through wide exchange networks in West Africa.
What lasted
The CUPRUM researchers describe Mauritania as an interface between two metallurgical traditions and as a sequence running from Neolithic to copper to iron. Akjoujt is therefore central to the question of how metalworking began in western Africa. Research on the sites has run from 1947 onward, though the project notes that a century of work has yielded limited information.
Where it stands today
The modern Guelb Moghrein copper mine was established at the site of the Grotte aux Chauves-souris. The mining company has given logistical support to archaeologists, and fieldwork continues to refine the dating, materials and methods of the ancient copper industry.
