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Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure. Coal is composed primarily of carbon along with variable quantities of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen.
煤的贡献者
Coal
事实证明 (测量) 储备,煤
能源; 煤
储备金或哪些吨位计算从透露在露头、 战壕、 运作和钻洞的尺寸和等级从详细采样结果计算的资源。为检验、 采样和测量的地点相距如此密切和地质特征很好定义的大小、 形状和矿物质含量是确立。计算的吨位和品位来判断要准确陈述的范围内并没有这种限制 20%以上判断为不同的计算的吨位或等级。 ...