DAKAR (Reuters) - Democratic Republic of Congo's revenues from its mining sector tripled year-on-year in the first quarter of 2018 to $397.86 million, finance ministry data showed. Revenues from the oil and gas sector dropped 10.87 percent year-on-year in the first quarter to $29.45 million, according to the data. Congo is Africa's top copper producer and the world's leading miner of cobalt. It also produces about 25,000 barrels per day of oil along its Atlantic coast. (Reporting By Aaron Ross; Editing by Raissa Kasolowsky)