Which mineral resource was important in Chad before oil was discovered?

Historically, the principal mineral resource of Chad was natron, a complex sodium carbonate.1

This mineral has long been economically significant, particularly in the Lake Chad and Borkou regions. It is traditionally excavated in blocks and utilized as salt, as well as in the production of soap and various medicines. While other mineral deposits such as gold, uranium, titanium, and bauxite exist within the country, natron served as the primary mineral resource prior to the development of the oil industry, which began production in 2003.12