The Lower Cretaceous salt deposits of the Gabon basin and Congo basin were laid down on top of an Early Cretaceous-Late Jurassic, continental graben fill that represents the rifting phase of the Afro-American continent. The salt is characterized by high percentages of potash and magnesium salts and a scarcity of sulfates and carbonates. The salt probably originated from a brine that was already enriched in highly soluble salts before entering the Gabon-Congo basins. Their low-solubility equivalents are found in the Cuanza basin of Angola. Commercial mining of the potash salt is only possible in those onshore areas where it is essentially undisturbed, shallow, and of the right chemical composition. These conditions are met in the Congo where the Holle mine production comes from rich sylvinite deposits.