Block of Coal

The Block of Coal (also known as Coal Block) is a mineral block that can also be used as a fuel.

Obtaining
Blocks of coal do not generate in maps naturally and must be crafted.

Crafting
Blocks of coal can only be crafted with regular coal, not charcoal. It is crafted in the same way as other mineral blocks.

Usage
Blocks of coal are often used to store coals in a compact fashion, or otherwise used as a fairly cheap construction block.

As a fuel
Blocks of coal can be used as fuel in a furnace. One block of coal smelts 80 items, which is more than the smelting time of the 9 coal items used to craft it. Note that since only 64 items can fit in the furnace at a time, to prevent wasting fuel you should restock the smelting items before they run out, and empty the output slot before it fills up. Hoppers come in handy for automating this, but be warned: using a hopper to unload a furnace forfeits any experience from the smelting.

Trivia

 * Cannot be crafted using charcoal due to logical issues with crafting and destroying.
 * Blocks of coal cannot be used as fuel for the minecart with furnace.
 * A full stack of Coal Blocks should smelt for 14.2 hours.
 * That is a little over fifty times as many items as a bucket of lava.
 * However, you will need 576 coal to do this.
 * 31,104 coal is needed to fill a large chest full of coal blocks with 64 blocks in each stack. This would smelt 276,480 items which is 80 large chests.