透闪石质玉中黄玉与糖玉致色成因差异研究

Study on difference of color genesis between yellow and brown tremolite jade

采用常规宝石学仪器并结合电子探针、电子顺磁共振谱及紫外-可见光谱等测试方法,对软玉中不同深浅的黄玉与糖玉样品进行了系统分析,以探讨其致色原因及其差异。分析结果表明,黄玉的致色原因主要为O^(2-)→Fe^(3+)的电荷转移跃迁及Fe^(3+)的^(6)A_(1)→^(5)T_(2)(D)跃迁,糖玉则主要由Fe^(3+)的^(6)A_(1)→^(4)E (D)、^(6)A_(1)→^(5)T_(2)(D)谱项跃迁与Mn;的Jahn-Teller效应致色。黄玉中O^(2-)→Fe^(3+)的电荷转移跃迁导致可见光区的412~500 nm处吸收,是形成与控制黄玉颜色的重要因素;而糖玉因含有Mn;致使黄绿色光被吸收而显示出黄绿色的补色。此外,Fe^(2+)—Fe^(3+)的荷移与Fe^(2+)(^(5)T_(2))+Fe^(3+)(^(6)A_(1))→Fe^(2+)(;E)+Fe^(3+)(^(6)A_(1))跃迁也对糖玉和黄玉的致色具有贡献。

Using conventional gemmological instruments along with electron probe microanalysis,electron paramagnetic resonance spectroscopy and ultraviolet visible spectroscopy,the samples of yellow and brown tremolite jade were studied,discussing the causes and differences of coloration elements in different dark and light samples.The main reasons for the coloration of yellow tremolite jade are the charge transfer transition of O^(2-)→Fe^(3+) and the^(6)A_(1)→^(5)T_(2)(D) transition of Fe^(3+),while the coloration of brown tremolite jade is mainly caused by^(6)A_(1)→^(4)E(D) and^(6)A_(1)→^(5)T_(2)(D) transitions of Fe^(3+) and Jahn-Teller effect of Mn;ions.The charge transfer transition of O^(2-)→Fe^(3+) in yellow tremolite jade leads to the absorption at 412~500 nm in the visible region,which is an important factor for forming and controlling the color of yellow tremolite jade,while the yellow green light absorption caused by Mn;in brown tremolite jade shows the complementary color of yellow green.In addition,the charge transfer of Fe^(2+)—Fe^(3+) and Fe^(2+)(^(5)T_(2))+Fe^(3+)(^(6)A_(1))→Fe^(2+)(;E)+Fe^(3+)(^(6)A_(1)) are also part of the reasons for the coloration of brown and yellow tremolite jade.