Alliance Resource Partners, L.P. operates as a diversified natural resource company primarily engaged in coal production and mineral and royalty interests. It is the second largest coal producer in the Eastern United States, with seven underground mining complexes that produce thermal and metallurgical coal for utility, industrial, and steelmaking customers. Additionally, the company owns and leases mineral interests in oil and gas producing regions, generating royalty income from these assets. Alliance Resource Partners serves both domestic and international markets, focusing on reliable energy solutions.