What is a long dead type of fuel?

Answer 1

A long-dead type of fuel is coal, particularly the anthracite variety, which was extensively used during the Industrial Revolution for steam engines and heating. While coal is still mined and used in some parts of the world, much of the high-quality reserves have been depleted, and the focus has shifted to cleaner energy sources. The environmental impact of coal mining and burning has led to a decline in its use, marking it as a relic of past energy practices.