Furnace

The furnace is a special block currently only available in the indev version of Minecraft. Before the furnace appeared, smelting was accomplished by creating a fire and dropping the ores into it. Now the furnace has its own smelting menu where several smelting operations can be done. It consists of one field for the object that will be smelted, one field for the output object and one field for a fuel. The fuel can be either trunk, plank, stick or coal. Each operation takes 10 seconds The different fuels have different burning times: The furnace will take time to smelt objects, but it will also work when the smelting menu is closed, as long as there are still objects to smelt and there's enough fuel. If all objects are smelted, the furnace will stop using fuel. When the fuel runs out, the heat in the furnace, indicated by the flame icon, will slowly decrease and when it is gone, the furnace will become inactive. If a smelting process was running, it will be aborted and has to be started again from the beginning
 * Coal burns for 1 minute and 20 seconds.
 * Logs and Planks burn for 15 seconds.
 * Sticks burn for 5 seconds.

The following smelting operations are known: