蕴藏在地壳里的矿产种类很多,而储量极其丰富。其中有一些象煤、铁、石油、铝礬土形成巨大的矿床,它们的储量要以几百万吨,甚至几十亿吨来计算。几十年来在我国一直开采着的类似这样的矿床的实例,就有顿巴斯煤田和库斯巴斯煤田,巴库油田和巴 There are many kinds of mineral deposits in the crust, and the reserves are extremely rich. Some of them form huge deposits of coal, iron, oil and bauxite, with reserves of millions or even billions of tons. Examples of such deposits that have been mined in our country for decades are the Donbas and Kusbasas coalfields, the Baku and the Pakistani