Coal is classified as a non-renewable resource.

Here's why:

• Formation Process: Coal is formed over millions of years from accumulated plant matter that undergoes intense pressure and heat. This process is called "coalification."
• Depletion Rate: The rate at which we extract and use coal far exceeds the rate at which it is naturally formed. Therefore, it is considered finite.

Once coal reserves are depleted, they will not be replenished within a human timescale.

For more information, you can consult the following resources:

• U.S. Energy Information Administration (EIA) - Where Coal Comes From