Why are coal and mineral fuel called non renewable source of energy?

Coal and mineral fuel are called non renewable source of energy because it is limited  in amount inside the earth and once it is used up we cannot use it again and again. Hence, it takes millions of years to reproduce. 

Coal is formed when dead plant matter submerged in swamp environments is subjected to the geological forces of heat and pressure over hundreds of millions of years. Over time, the plant matter transforms from moist, low-carbon peat, to coal, an energy- and carbon-dense black or brownish-black sedimentary rock.Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements; chiefly hydrogen, sulfur, oxygen, and nitrogen.Anthracite: The highest rank of coal. It is a hard, brittle, and black lustrous coal, often referred to as hard coal, containing a high percentage of fixed carbon and a low percentage of volatile matter.

A carbonaceous fuel mined or stripped from the earth, such as petroleum, coal, peat, shale oil, or tar sands is called mineral fuel. Mineral fuels are found in sedimentary rocks.Fossil fuel is a general term for buried combustible geologic deposits of organic materials, formed from decayed plants and animals that have been converted to crude oil, coal, natural gas, or heavy oils by exposure to heat and pressure in the earth's crust over hundreds of millions of years.