Non-renewable resource are resources that form extremely slowly
and those that do not naturally form in the environment. Minerals are the most
common resource included in this category. By the human perspective,
resources are non-renewable when their rate of consumption exceeds the rate
of replenishment/recovery.
Some resources actually naturally deplete in amount without
human interference, the most notable of these being radio-active
elements such as uranium, which naturally decay into heavy
metals. Of these, the metallic minerals can be re-used by
recycling them, but coal and petroleum cannot be recycled.