Non-renewable resources can generally be separated into two main categories; fossil fuels and nuclear fuels.

Fossil Fuels

Fossil fuels are derived from organic matter which has been trapped between layers of sediments within the Earth for millions of years. Examples are crude ol/petroleum, gas and coal

Nuclear Fuels

The other form of non-renewable resource used to produce energy, nuclear fuels, is primarily obtained through the mining and refining of uranium ore.