桂林新型水热法合成祖母绿的宝石学特征

GEMMOLOGICAL PROPERTIES OF A NEW TYPE OF GUILIN HYDROTHERMAL SYNTHETIC EMERALD

桂林新型水热法祖母绿为厚板状或短柱状晶体 ,翠绿色或带蓝色调的绿色 ,c( 0 0 0 1 )、 m( 1 0 1 0 )、 a( 1 1 2 0 )晶面发育 ;主成分 Si O2 及 Al2 O3含量略高于天然祖母绿 ,Cr2 O3含量在 0 .3%～ 0 .5%之间 ;吸收谱显示铬离子吸收 ,红外谱显示水的存在 ,且在 50 0 0～ 550 0 cm-1范围内有 51 0 9,52 74 ,544 8cm-13个特征吸收峰 ,在 34 0 0～ 4 0 0 0 cm-1范围有 370 1 cm-1单峰 ;有特征的渣状包裹体、硅铍石晶质包裹体、气液两相包裹体和规则的生长纹。其它特征与 Linde、Biron。

The new type of Guilin hydrothermal synthetic emerald is thick plate or short prismatic crystal with bluish green or green colour. Its crystal configuration consists of two hexagonal prism a (1120) and m (1010) and the basal pinacoid c (0001). EPM analyses show that SiO 2 and Al 2O 3 are more than those of natural emeralds and Cr 2O 3 is similar to that of natural and other synthetic counterparts. Visible absorption spectra show Cr 3+ absorption peak. IR spectra show typical water absorption and characteristic absorption peaks of 5109, 5274 and 5448cm -1 in the range of 5000～5500cm -1 as well as only one peak of 3701cm -1 in the range of 3400～4000cm -1 . Typical dreg inclusions, bertrandite crystalized inclusions, two phase inclusions and regular growth line are discovered in the crystal. Other properties of the new type of Guilin hydrothermal synthetic emerald are similar to those of Linde, Biron and Tairus hydrothermal emeralds.