With the exception of oil, Benin was relatively poor in mineral resources, all of which belonged to the government. Sedimentary phosphate deposits were located along the Mekrou River in the north. There was low-grade iron ore at Loumbou-Loumbou and Madekali, in the Borgou district, where surveys discovered resources of more than 500 million tons. Development of the hydroelectric power station was seen as a key factor in the future potential development of the iron ore and phosphate deposits. Limestone was quarried for use in cement plants. There was potential for small-scale gold mining in the Atacora gold zone, in the northwest. Other mineral resources included chromium, rutile, and diamonds; small quantities of industrial diamonds were exported. In 2000, the country produced 450,000 tons of hydraulic cement, and 500 kg of gold.