Nonrenewable Resource
A nonrenewable resource exists in a fixed amount or forms far more slowly than it is consumed, such as coal, oil, natural gas, and minerals.
Definition
A nonrenewable resource is something from nature that forms so slowly it is effectively finite on human timescales, including fossil fuels such as coal, petroleum, and natural gas, which formed from buried organic matter over millions of years, and mineral resources such as iron, copper, gold, and phosphate, which are concentrated by geologic processes and cannot regrow, though metals themselves can be recycled indefinitely. These are stocks rather than renewable flows, and their economics follow depletion models such as Hubbert's curve, where the distinction between reserves, what is economically recoverable now, and the total geologic resource shifts with price and technology, which is why predictions of imminent exhaustion have repeatedly failed even as environmental limits have tightened and ore grades at the richest deposits have declined over time.
Example
The gasoline in a car comes from oil that took millions of years to form underground, and once burned it is gone for good, while North Carolina mines nonrenewable phosphate near Aurora for fertilizer and lithium-bearing spodumene near Kings Mountain even though it has little coal or oil of its own. Copper ore grades have fallen from over $2\%$ a century ago to under $0.6\%$ today, so mining a single tonne of copper now requires moving several hundred tonnes of rock, while uranium for nuclear power remains nonrenewable even though breeder reactors and seawater extraction could extend supplies by orders of magnitude.
Key Insight
Earth is still making oil and coal today, just so slowly that for practical purposes it might as well be never, and metals are nonrenewable but not consumed, since the copper in an old phone can be recycled forever even though the coal that generated the electricity to charge it cannot. The real limit on a nonrenewable resource is rarely the last tonne left in the ground; it is the point where extracting it costs more in energy, money, or environmental damage than it returns.