你如果能够到山上去游玩一趟,那时你会增长许多见识。在我们日常生活里,总认为所有的石头好像都差不多一样硬,而实际上却不是这样。这一点,只要拿一块烧石灰用的石灰石和一块雕刻图章用的水晶石来比比,就很容易看出来。水晶比石灰石要硬得多,水晶硬度为七,而石灰石硬度仅为三。石头中最软的要算滑石,很容易用铁片划破;金刚石(俗称夜明珠)却完全相反,它比一切其他矿物都硬。软的滑石在油漆工业、橡胶工业、陶瓷工业、造纸工业以及纺织工业上都有重要作用,另外它还可以制成 If you can take a trip to the mountains, then you will grow many insights. In our daily lives, we always think that all the stones seem to be almost the same, but in reality it is not. This can be easily seen by taking a piece of limestone for lime burning and a crystal stone for engraving. Crystal is much harder than limestone. The hardness of the crystal is seven, and the hardness of limestone is only three. The softest talc in the stone is easily scratched with a piece of iron. Diamond (commonly known as the Night Pearl) is the opposite. It is harder than any other mineral. Soft talc has an important role in the paint industry, the rubber industry, the ceramics industry, the paper industry and the textile industry. It can also be made