Operating cash flow and free cash flow in the mineral rights segment each declined $1 million year over year. Nunez said both metallurgical and thermal coal markets had stabilized and improved modestly from recent lows, though he declined to predict commodity-price movements. On thermal coal, Nunez said higher oil prices can encourage associated natural gas production, potentially pressuring North American thermal coal prices. Operating cash flow and free cash flow for the soda ash segment each fell $5 million from a year earlier. About Natural Resource Partners (NYSE:NRP)Natural Resource Partners LP (NYSE: NRP) is a master limited partnership that acquires and manages royalty and other mineral interests in coal and other natural resources across North America and Australia.