北京地质博物馆院内,有两棵一亿年前的粗大古树干。其中来自辽宁省的一棵,木纹清晰,从木纹数目看,本身已有150年的树龄。表面看来,它们都象大树,但仔细一看,却都变成了坚硬的石头。变成石头的古木,就是硅化木,也称木化石。称硅化木的原因,是因为石化了的古树成分,主要是二氧化硅(也有碳酸钙、硫化铁等其他成分)。它们是在漫长的地质年代中,逐渐被水中二氧化硅等矿物质渗透和替代,形成了保留木质结构的石头。据记载,木头变石头的原因,我国在古代已经知道。唐朝大诗人陆龟蒙有诗曰:“东阳多名山,金华为最大。其间饶古松,往往化为石。”并且指出:“松木入水历一千年则化为石。”古代对硅化木的认识,使英国科学家李约瑟也惊叹道:古植 Beijing Institute of Geology Museum, there are two 100 million years ago, the ancient tree trunk. One from Liaoning Province, a clear wood, from the number of wood look, itself has 150 years of age. On the surface, they are like trees, but after a closer look, they become hard stones. Into the ancient stone, is the silicified wood, also known as wood fossils. The reason for the silicified wood is that the petrified old tree is mainly composed of silica (there are also other components such as calcium carbonate and iron sulfide). They are gradually penetrated and replaced by minerals such as water and silica in the long geologic age, forming the stone that preserves the woody structure. According to records, the reason that the stone becomes the stone in our country already knew in ancient times. The great poet Lu Guimeng of the Tang Dynasty wrote a poem saying: “There are many mountains in Dongyang and Jinhua is the largest. In the meantime, Rao Gusong often turns into stone.” “It also states:” pine enters the water for a thousand years and turns into stone. " Silicified wood awareness, so that the British scientist Joseph Needham also exclaimed: ancient planted