n (and smaller amounts of other elements) gradually dissociate from the plant matter, increasing its relative carbon content.
Coal also contains inorganic components, known as ash. Ash includes minerals such as pyrite [24] and marcasite [25] formed from metals that accumulated in the living tissues of the ancient plants. Quartz [26], clay, and other minerals are also added to coal deposits by wind and groundwater [27]. Ash [28] lowers the fixed carbon content of coal, decreasing its heating value.
NOTES TO THE TEXT
[1] sedimentary rock：沉积岩
[2] tropical swamps：热带沼泽
[3] Lush vegetation：茂盛的植物
[4] club mosses：石松
[5] horsetails：马尾（木贼属的一种植物）
[6] layers of mud and sand：泥砂层
[7] decayed plant material：腐烂的植物材料
[8] peat：泥炭
[9] minerals：矿物
[10] lignite：褐煤
[11] subbituminous coal：次烟煤
[12] bituminous coal：烟煤
[13] anthracite：无烟煤
[14] Permian：二叠纪
[15] Triassic：三叠纪
[16] Jurassic：侏罗纪
[17] Cretaceous：白垩纪
[18] Tertiary：第三纪
[19] cellulose：纤维素
[20] reinforcing material：加固的材料
[21] cell walls：细胞壁
[22] lignin：木质
[23] tannins：丹宁，鞣酸
[24] pyrite：黄铁矿
[25] marcasite ：白铁矿
[26] quartz：石英
[27] groundwater：地下水
[28] ash：灰分
