江苏六合蓝宝石改色机理初步探讨

PRELIMINARY RESEARCH ON THE MODIFIED COLOUR OF SAPPHIRE IN LIUHE COUNTY,JIANGSU PROVINCE

作者根据刚玉矿物的呈色原理,选择合适的外界条件和工艺流程,对六合蓝宝石成功进行了改色试验,对其变色机理作了初步探讨。

The sapphire placer,enriched in the diluvion and alluvium nearby old crater of the Cenozoic Era in Liuhe county,is most of the dark and subtransparent colour.The colour causing ions are conjecturally to be mainly composed of Fe^(2+) and Ti^(4+) according to genetic environment of sapphire.The main factors affected sapphire coloration are the content of colour causing ions and vatence states as well as constitution forms,which owing to different element constitution and ions vatence states,there exists a obvious difference for the coloration of sapphire,and the content of colour causing ions also affects directly the density of colour.By changing external conditions i.e.selecting favourable medium,temperature,pressure and additive,and using a treat method of high temperature and controlled pressure,the colour of Liuhe sapphire has been modified successfully.The efficency of modified colour is characteristic of perfect colour and higher transparency. As experiment conditions and analysis measures are limited,colour modification of Liuhe sapphire is roughly due to that the vatence state of colour causing ions and constitute form are changed and material secretion is transformed from inside to outside.In short,the transit of Fe^(2+) to Ti^(4+) can form a wide absorption band from yellow to red and lead to modified colour when exerting certain energy on sapphire.It is possible for unstable materials such as Fe,Ti and Mn ions inside sapphire to secret outside.That could decrease total quantity of colour causing ions inside sapphire and fade sapphire colour as temperature and pressure are increased.Additionally,the distribution forms of inside impurities which have seriously affected transparency of sapphire are also changed and resulting a uniform distribution and good trans- parency. Through many times experiments,the method modified sapphire colour can not only be used on Liuhe sapphire placer effectively but also some sapphires in the globe.