Block of Coal

The block of coal is a compact way to store coal, and can be used for decoration and fuel.

As a fuel source, it can smelt 80 items.

Crafting
Blocks of coal can only be crafted with regular coal, not charcoal.

As a crafting ingredient
A block of coal can be crafted back into 9 coal items, making it useful as a storage 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).

Trivia

 * Cannot be crafted using charcoal due to logical issues with crafting and destroying.
 * Blocks of coal use the same texture as block of redstone, but black instead of red.
 * Blocks of coal cannot be used as fuel for the minecart with furnace.
 * A full stack can cook little over fifty times as many items as a bucket of lava.