Coal is a black or brown combustible sedimentary rock formed from ancient plant matter buried and compressed over millions of years. In Chinese, 煤炭 (méi tàn) is the formal, standard compound noun for 'coal' — it’s more commonly used in written contexts, official reports, energy discussions, and academic or industrial settings than the standalone character 煤. The first character 煤 means 'coal' on its own and carries the core semantic meaning; the second character 炭 means 'charcoal' or 'carbon-based fuel', reinforcing the idea of a carbon-rich, burnable material.

This compound reflects a common pattern in Chinese where two semantically related characters combine to form a precise, unambiguous technical term. While 煤 can sometimes be used alone in informal speech (e.g., 煤很便宜), 煤炭 is preferred when referring to coal as a natural resource, commodity, or energy source — especially in policy, mining, environmental science, or economic reporting.