Minecraft resource gathering/Coal
Coal is found underground on any level and can be mined with any pickaxe. If you use a pickaxe enchanted with Silk Touch, it will drop the ore, which is pretty useless exept for decoration. If your pickaxe is enchanted with fortune, you will get multiple pieces of coal.
Coal can also drop from the dangerous Wither Skeleton.
Coal can be used as a fuel. One piece of coal can smelt 8 items. However a Block Of Coal (crafted with 9 coal) can smelt 80 items. Blocks of coal can also be used as decoration. If you like the way they look, you might want to use charcoal, blaze rods, or lava as your primary source of fuel instead.