The most reliable source of Coal is the Mines . You can find Coal deposits scattered throughout the Mine levels, often appearing as black, lumpy rocks. They are more common on deeper levels, but can be found on any floor.

Coal is a versatile resource with several critical applications: Smelting: Coal is required in Furnaces to smelt ores (Copper, Iron, Gold) into their respective bars. Each smelting operation consumes 1 Coal.

Coal — Stardew Valley Guide

Redirecting to Coal — Stardew Valley Guide