"Угольные" refers to coal, a black or brownish-black sedimentary rock primarily composed of carbon. It is formed from the remains of ancient plants that have undergone heat and pressure over millions of years. Coal is a significant source of energy and is used for electricity generation, heating, and in various industrial processes. There are different types of coal, including антрацит, битуминозный уголь, and лигнит, each with varying carbon content and energy output. The extraction of coal occurs through mining, which can be surface or underground. Despite its usefulness, coal mining and combustion have environmental impacts, contributing to air pollution and climate change.