Coal
- Not to be confused with Charcoal
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. Coal is formed when dead plant matter decays into peat and is converted into coal by the heat and pressure of deep burial over millions of years. Coal is primarily used as a fuel. Coal is very soft ranking from 2 to 4 on the Mohs hardness scale, while sandstone ranks from 5 to 7.
Materials needed
Coal is a naturally occurring material
Crafting instruction
Coal is extracted from mines
Uses
Because of its hot, consistent burning temperature and relative abundance, coal has had widespread use across history in heating, metalworking and powering coal engines. coal burns at a higher temperature than wood, and so allowed for easier production of iron and other metals. This high temperature also allowed for particularly high pressures to be achieved in steam engines with a lower volume of fuel. This ease of energy extraction was the basis of the industrial revolution.
Raw coal is often not desirable for making steel due to impurities such as Sulfur and other volatiles. This can be fixed by "coking" the coal to turn it into Coke which is the process of heating coal in the absence of oxygen at 600 degrees celsius for around 24 hours. This removes the impurities, which yields a fuel that can burn hotter than raw coal and can be added to Steel without contamination with compounds that lower its strength.
Dependencies
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References
| This article uses material from the Wikipedia article Coal, which is released under the Creative Commons Attribution-ShareAlike 3.0 Unported License (view authors). | 
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