NMDC Limited, formerly National Mineral Development Corporation, is an Indian public sector undertaking involved in the exploration of iron ore, copper, rock phosphate, limestone, dolomite, gypsum, bentonite, magnesite, diamond, tin, tungsten, graphite, coal etc. It is India's largest iron ore producer and exporter, producing more than 35 million tonnes of iron ore from three mechanized mines in Chhattisgarh and Karnataka. It also operates the only mechanized diamond mine in the country at Panna in Madhya Pradesh. Wikipedia