Coal
What a fuel ore becomes in a smelter: a dense black lump that burns far longer and harder than the raw ore.
A metal ore smelts into an Ingot you can beat into something. A fuel ore has nothing in it to beat: it's the burning part. So the smelter bakes it down into coal instead.
Coal keeps the properties of the ore it came from, so a fiercer seam makes fiercer coal. Raw fuel ore still burns if you're in a hurry, for 2 to 12 seconds at 1 to 6 power a second depending on its Combustion. Coal manages 2.1 times both.
Used for
- Fuel for a Generator.
- Two coal go into every Thruster.
- Coal with Combustion 85+ (only from a dust world's signature ore) packs an Ignition Charge.