Copper Furnace is a machine that is included with the Base Metals. It is an upgraded version of the vanilla Minecraft furnace, and is crafted by surrounding one with 8 Copper ingots. Being slightly faster, it is more efficient than the vanilla furnace. It can be upgraded into the Bronze Furnace, the next upgraded version, by surrounding it with 8 Bronze ingots.
It takes 9.5 seconds for a copper furnace to heat one object. Alternatively, one piece of coal will heat 8.42 objects. This makes it minimally more efficient as it still takes 7.6 coal (aka 8) to heat a whole stack of material.