As the best bodies of ore are exhausted, miners move on to less concentrated deposits in more difficult natural circumstances. These mines cause more pollution and require more energy.

含量的百分率愈大，品位愈高-译注最好的矿砂开采殆尽，矿主们会转向开采那些品位不好的矿，但会面临更困难的自然条件，开采这些矿会带来更多的污染，也会需要更大的能耗。

Flashes through Radden's following closely, evaded the American election the human tide, has hidden the ore difficult fierce detonation, bypassed Southeast Asia the tsunami attack.

闪过拉登的盯梢，避过美国大选的人潮，躲过矿难的剧烈爆炸，绕过东南亚的海啸袭击。

Alunite is a harmful impurity which is difficult to remove from kaolinite and so is kaolinite in alunite ore.

明矾石是高岭土中难以除去的有害杂质，高岭石也是明矾石矿石中的有害杂质。