The high-grade manganese deposits at Moanda, near Franceville, are among the world's richest. Reserves were estimated at 250 million tons with a metal content of 48%–52%. Production had been limited to a ceiling of 2.8 million tons a year, corresponding closely to the capacity of the cableway—at 76 km, Africa's longest overhead cable—used to transport the mineral to the Congo border, from where it was carried by rail to the port of Pointe Noire. The newer Trans-Gabon Railway provided an alternate export outlet through the Gabonese port of Owendo, and the cableway was made redundant. Use of the railroad has cut shipping costs by $20 million per year. Before nationalization, Manganese was exploited by the Mining Co. of L’Ougoué, which ranked among the world's lowest-cost producers. In 2004, an estimated 2.4 million metric tons of metallurgical-grade ore were extracted, up from 1.95 million metric tons in 2003. Annual production capacity at the Moanda Mine was 2.5 million tons, which amounts to around $5,442,000,000 a year, with reserves estimated to last 100 years. In 2012, BHP Billiton were developing a second manganese deposit.
Cement
Gabon also produced an estimated 350,000 metric tons each of clinker and hydraulic cement in 2004. Also in that year an estimated of diamonds were produced, along with 70 kg of gold.
Iron
The Mékambo and Belinga iron fields in the northeastern corner of Gabon are ranked among the world's richest. Reserves are estimated as high as 1 billion tons of ore of 60%–65% iron content, and production could reach 20 million tons a year. Although iron was discovered there in 1895, it was not until 1955 that a full-scale commercial license was issued. Exploitation still awaited the establishment of a 225 km extension of the Trans-Gabon Railroad from Booué to Belinga; construction has been considered unprofitable, because of unfavorable market conditions.
Other minerals
The potential for new developments in niobium, gold, manganese, and possibly phosphate suggests a continued role for mining in the economy. The lack of adequate infrastructure inhibits new grassroots exploration and remains a major constraint on development of the well-defined iron ore deposit at Bélinga.
