玻利维亚浅蓝绿色磷叶石的宝石矿物学特征

Gemmological and Mineralogical Characteristics of Light Blue-Green Phosphophyllite from Bolivia

磷叶石是一种稀有宝石,目前国内关于磷叶石的宝石学和谱学特征研究较少。利用X射线荧光光谱(XRF)、电子探针(EPMA)、激光拉曼光谱仪(Raman)、红外光谱仪以及紫外-可见分光光度计等测试仪器对产自玻利维亚的浅蓝绿色磷叶石样品进行详细测试与分析。XRF分析显示,Fe、Zn、P为磷叶石的主量元素,此外磷叶石中还含有Mn、Na、K、Ca等微量元素;利用电子探针对玻利维亚磷叶石样品中的Fe、Zn、P和Mn元素进行定量分析,经计算得到平均分子式为Zn_(2.18)(Fe_(0.92)Mn_(0.01))(P_(0.99)O_(4))_(2)·4H_(2)O;拉曼光谱测试显示,325 cm^(-1)处的拉曼峰由M-O(M为金属阳离子Zn^(2+),Fe^(2+),Mn^(2+))振动引起;422、590、943、997、1073和1137 cm^(-1)处的拉曼峰由PO_(4)^(3-)引起;1602、3153、3374、3566 cm^(-1)处的拉曼峰由水分子振动引起。玻利维亚磷叶石的深褐色伴生矿物为闪锌矿,拉曼位移为228、304、351 cm^(-1);红外光谱测试显示,400~1200 cm^(-1)范围内的谱带由PO^(3-)_(4)引起,1600~3600 cm^(-1)范围内的谱带由水分子振动引起,磷叶石上白色伴生矿物为伊利石,吸收峰位于3650、3625、3425、1646、1028、538、474、418 cm^(-1)处;紫外-可见光谱测试发现磷叶石吸收谱线与蓝绿区380、448、467 nm的三条较强吸收带(铁谱)特征一致,表明玻利维亚磷叶石主要致色元素为Fe^(2+)。其501 nm处的吸收带与锰谱特征一致,表明玻利维亚磷叶石的致色元素可能还有Mn^(3+)。

Phosphophyllite is a rare gemstone.Currently,there is little gemmological and spectroscopic characteristic study on phosphophyllite in China.Detailed determination and analysis of a light blue-green phosphophyllite sample from Bolivia was carried out by X-ray fluorescence spectroscopy(XRF),electron probe(EPMA),laser Raman spectrometer(Raman),infrared spectrometer,UV-Vis spectrophotometer and other test apparatuses.XRF analysis showed that Fe,Zn,P were the main elements of phosphophyllite,and there were Mn,Na,K,Ca and other trace elements in phosphophyllite.The quantitative analysis of Fe,Zn,P and Mn elements in Bolivian phosphophyllite was carried out by electron probe.The average molecular formula was Zn_(2.18)(Fe_(0.92)Mn_(0.01))(P_(0.99)O_(4))_(2)·4H_(2)O.Raman spectrum test shows that the Raman peak at 325 cm^(-1) is caused by M-O(M is metal cation Zn^(2+),Fe^(2+),Mn^(2+))vibration,and the Raman peak at 400-1200 cm^(-1)is caused by PO_(4)^(3-),the Raman peaks at 1602,3153,3374 cm^(-1)and 3566 cm^(-1)are caused by the vibration of water molecules.The dark brown associated mineral on the phosphophyllite sample from Bolivia is sphalerite,and the Raman shifts are at 228,304,351 cm^(-1).Infrared spectrum test shows that the band in the range of 400-1200 cm^(-1)is caused by PO_(4)^(3-),and the band in the range of 1600-3600 cm^(-1)is caused by the vibration of water molecules,and the white associated mineral on phosphophyllite sapmle from Bolivia is illite,whose absorption peaks are at 3650,3625,3425,1646,1028,538,474,418 cm^(-1).The UV-Vis spectrophotometer test shows that the absorption line of phosphophyllite is consistent with the ferrographic characteristic of three strong absorption bands at blue-green region of 380,448 nm and 467 nm,indicating that the main chromogenic element of phosphophyllite is Fe^(2+).The absorption band at 501 nm was consistent with the manganese spectroscopy characteristic,indicating that the chromogenic element of phosphophyllite may also be Mn^(3+).