It is known that metals are very important in our life. Metals(金属) have the greatest importance for industry. All machines and other engineering constructions（结构） have metal parts, some of them consist only of (由…构成) metal parts.
There are two large groups of metals:
1)Simple metals – more or less (或多或少) pure chemical elements.
2)Alloys（合金） – materials consisting of simple metal combined with （与…结合） some other elements（元素）.
About two thirds of all elements found in the earth are metals, but not all metals may be used in industry. Those metals which are used in industry are called engineering metals (工程金属). The most important engineering metal is iron (Fe)（铁）, which in the form of alloys with carbon(C) （碳元素）and other elements, finds greater use than any other metal. Metals consisting of iron are called ferrous metals (黑色金属). The most important nonferrous metals are copper (Cu)（铜）, aluminum (Al)（铝）, lead (铅) (Pb), zinc（锌） (Zn), tin(锡) (Sn), but all these metals are used much less than ferrous metals, because the ferrous metals are much cheaper.
Engineering metals are used in industry in the form of alloys because the properties（特色）of alloys are much better than the properties of pure metals. Only aluminum may be largely used in the form of simple metal. Metals have such a great importance because of their useful properties or their strength, hardness, and plasticity（弹性）.
Different metals are produced in different ways, but almost all the metal are found in the form of metal ore（矿石） (iron ore, copper ore, etc)
The ore is a mineral (矿物质) consisting of a metal combined with some impurities (杂质) . In order to produce a metal from some metal ore, we must separate these impurities（杂质） from metal that is done by metallurgy (冶金术) .
Vocabulary
1. metal n. 金属
2. construction n. 结构
3.combine … with 把…和…结合(起来)
4. iron n. 铁
5. carbon n. 碳
6. ferrous a.（含）铁的；二价铁的~ metals 黑色金属
7. nonferrous metals 有色金属
8. copper n. 铜
9. aluminium n. 铝
10. lead n. 铅
11. zinc n. 锌
12 tin n. 锡
13. metallurgical a. 冶金（学）的
14. strength n. 强度；实力
15. hardness n. 硬度
16. plasticity n. 可塑性，适应性
17. ore n. 矿；矿砂（石）
18. impurity n. 杂质；不纯
19. mineral n. & a. 矿物（的）
20. metallurgy n. 冶金；冶金术
