Coal
Coal is a combustible black or brownish-black sedimentary rock, formed as layers called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen.
Coal is a combustible black or brownish-black sedimentary rock, formed as layers called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen.
Coal is a combustible black or brownish-black sedimentary rock, formed as layers called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen.
Source: Wikipedia "Coal" · CC BY-SA 4.0
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