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 72 items, the same as 9 coal which went into its construction. 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).

Usage
Blocks of coal can be used as a better way to smelt more items at one time. It multiplies the effect of one coal smelting 8 blocks by 9, producing a total of 72 blocks to smelt.

Trivia

 * Cannot be crafted by charcoal according to dinnerbone, the reason for this is that it would be immensely hard to code, as coal and charcoal share the same item id.
 * Uses the same texture as block of redstone, but black instead of red.
 * Like horses, the block of coal is one of the few features in the April fools of Minecraft 2.0 that did eventually get into the game.
 * The Block of Coal cannot be used as fuel for the Minecart with Furnace

Kohleblock Charbon (bloc) 石炭ブロック