Green copper fire that melts ores

Using flint and steel on any copper block will create a new green fire in addition to regular fire and blue fire.
Green fire is able to melt ores that have fallen into it, as it does with food on a campfire. The green fire does not melt the entire stack at once, but melts items one by one until it goes out. The green fire is only suitable for smelting ore.
This will be useful if the player in the cave wants to melt a couple of ores, but they does not have a furnace and has run out of coal.