人类认识和利用金属只有几千年的历史,而在这以前的几万年的漫长时期,则是用石头、木头和骨头来制做劳动工具.这就是石器时代.人类最早使用的金属是金、银和铜.这些金属常以自然状态存在,外表特征很容易鉴别,同时不需加工处理就可以利用.但它们都比较软,不能代替燧石或玉石等来制做刀、斧或锤之类的工具,而只能用作装饰品和生活器具.大约在六千年以前,人类在生产实践中发现一种绿色的石头经过烧炼后可转变为钢.虽然铜比较容易开采和加工,但由于不够硬也不适于作劳动工具.后来,人类又开始炼银、铅和锡,同时 Humans have only known and used metals for thousands of years. In the long period of tens of thousands of years before, they used stone, wood, and bones as tools of labor. This was the Stone Age. The earliest metal used by humans was gold. , silver and copper. These metals often exist in their natural state. The appearance characteristics are easily identified and can be used without processing. However, they are relatively soft and cannot be used to make knives, axes, hammers, etc. instead of vermiculite or jade. The tools, which can only be used as decorations and living utensils. About 6,000 years ago, humans discovered in production practice that a green stone could be transformed into steel after being refined. Although copper is relatively easy to extract and process, Because it is not hard enough, it is not suitable as a working tool. Later, humans began to smelt silver, lead and tin.