汉白玉的宝石学特征与质量评价

On character of white marble and quality prospect

由于市场经济发展的需要,对物美价廉且产量大的汉白玉料需求量急增.长期以来对该玉料深入研究较少.笔者对国内五个地区的汉白玉样品进行较系统的宝石学特征研究,其化学成分CaO含量28.86%～33.21%,MgO17.13%～21.36%,矿物成分主要以白云石为主(92%～97%),方解石为1.5%～5.6%;结构多为细粒变晶结构;摩氏硬度为4.02～4.43;密度为2.70～2.81g/cm3.结合前人研究提出汉白玉有白云石型和方解石型2类.且前者质量优于后者.按矿物纯度、洁白度、细腻度、瑕疵发育度等质量评价因素将汉白玉划分5个等级.

The development of white marble, one average and lowgrade jade, has a long history in China. It's extensively used as building materials for palace and temple, but there is lack of identification and research for it. At present, as the development of market economics, in addition to the architecture, the need in jewely, handcraft articles and so on are increased, especially for the white jade (white marble). Here is a systematical research for the gemstones characters of the white marble samples from five areas with some findings:chemical composition,CaO28.86%～33.2%,MgO17.13%～21.36%.It mainly is in the form of dolomite (92%～97%),and calcite 1.5%～5.6%,moss scal hardness 4.02～4.43,SG2.70～2.81,the texture can mainly be finegrained crystalloblastic. Two kinds of the white marble are introduced:dolomite and calcite,the former is better than the latter. The white marble can be classified into five grades,such as pure, white exqusite flaw and so on. It is important to protect whether the transaction is fair or not in the market.