Coal

Coal is found as a resource in the form of Coal Ore, and must be mined in a Coal Mine and then converted to Coal in a Coal Processing plant.

Coal is arguably one of the most important resources in the game as it is required to manufacture Bricks, Cement, create heat (without the use of mods), and is the best early game way of generating power, with nuclear energy being the superior option once you have the resources to built the nuclear plant and surrounding industry.

i recommend the utilization of Cableways to move the ore from mine to plant as it is a much faster method then most other methods in my experience.