便携式近红外光谱对层状硅酸盐矿物结构及成因探讨

采用ore XpressTM便携式矿物分析仪获取了高岭石、蛇纹石、滑石、叶腊石、白云母五种层状硅酸盐的近红外光谱谱图,运用矿物学和近红外光谱原理研究发现:二八面体型层状硅酸盐由于八面体空隙的存在,使谱图上1400nm和1900nm附近处的吸收峰强度要强于三八面体型层状硅酸盐的吸收峰强度,并且二八面体型层状硅酸盐的结构单元层是1:1型,因此氢键效应会加剧这种作用;结构单元层类型相同的层状硅酸盐,因八面体片中的阳离子电负性不同,会使金属一羟基叠加峰峰位发生偏移;过渡离子的存在,会使吸收峰的峰强和峰形产生异常;利用不同矿物晶格中分子、离子吸收不同能量的光子后,会在图谱上表现出不同的吸收特征,可反映出样品的矿物类型、结晶度、含水量等信息。

THE PORTABLE NEAR-INFRARED SPECTROSCOPIC STUDY OF THESTRUCTURE AND GEOLOGICAL GENESIS OF LAYERED SILICATE MINERALS

We hasobtained near-infrared spectrogram of kaolinite, serpentine, talc, pyrophyllite, and muscovite and using the principles of mineralogy and spectroscopy, we find that the absorption peak intensities around 1400 nm of dioctahedralphyllosilicates are much stronger than the trioctahedral phyllosilicate due to the octahedral voids,if the minerals also has a 1:1 type structure, it may add multiple spectral bands because of hydrogen bonding effect; Phyllosilicates with the same type of structural unit layer can make the positions of overlapping peaks produced by metals and hydroxies offset when kations have different electronegativities in the octahedral sites; The existence of transition ions will make peak intensities and shapes abnormal; There are different features on the near-infrared spectrogram when different molecules and ions absorbed photons with different energys and we analyzed the cause of the similarity and dissimilarity for different absorption bands which can reflect mineral types, crystalline, water content, etc. The technology of portable near- infrared mineral analyzer is widely used in minerals and ore deposits with its small size, easy to carry, etc. The technology of near-infrared mineral analysis has many advantages than the traditional methods. With the development of near-infrared technology, it will be more and more applied in geological field and can play a role part in ore and oil exploration.