新疆祖母绿宝石矿物学特征初探

新疆地区首次发现了质量好、品级高、颜色正、块度大的优质祖母绿宝石,从宝石矿物学特征角度对新疆祖母绿宝石矿物学特征进行了初步研究,发现新疆祖母绿宝石可见光吸收光谱特征明显,红区683 nm、680 nm强吸收线,662 nm、646 nm弱吸收线,橙黄区630～580 nm部分吸收带,紫区全吸收.祖母绿样品晶胞参数测定结果为a=0.9233 nm,c=0.9206 nm,Z=2,主要粉晶谱线为2.871(100),3.257(100),7.996(100).对新疆祖母绿样品进行了红外反射光谱测试,新疆祖母绿样品与所使用IRprestige-21 傅里叶变换红外光谱仪中祖母绿对比样的红外反射光谱耦合较好.新疆祖母绿其化学成分中含Cr2O3较高,一般在0.21%～0.54%之间,可能是我国已经发现的质量最好的祖母绿宝石.

GEMOLOGICAL FEATURES OF XINJIANG EMERALD

The pure color and big block-shaped emeralds were recently discovered in Xinjiang. This paper has drawn a conclusion on Xinjiang emeralds from the perspective of gemology. The emeralds have obvious characteristic absorption visible light spectra. In the red zone strong absorption lines appear at 683 nm and 680 nm, and weak absorption lines at 662 nm and 646 nm. In the orange zone part of absorption band appears at 630-580nm and in the purple zone there is a wide absorption. The results are: the unit cell parameters: a=9.233 nm, c=9.206 nm, Z=2, the main powder lines are 2.871 (100), 3.257 (100), and 7.996 (100). On the sample FTIRS tests, an ideal emerald FTIRS fitting is achieved. Emeralds from Tashkurghan, Xinjiang contain higher Cr2O3, generally within the range of 0.21%-0.54%. Maybe they are the best emeralds discovered ever in China.