[Spectra and Mineralogy Study on Black Tianhuang and Kengtou Stone from Shoushan, Fujian Province].

Shoushan Stone is one of the national stones of our country which is also the most famous stone of the four outstanding seal stones in China. As to Shoushan stones, black Tianhuang stone is a kind of black colored stone. It is one of the most special species in Tianhuang stones which comes from fields beside the Shoushan Brook. The black Kengtou stone comes from Kengtou Zhan, its original place. In this study, black Tianhuang stone is studied and compared with black Kengtou stone by using X-ray powder diffraction spectrometer (XRD), infrared spectrometer (IR), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and scanning electron microscopy (SEM) in order to analyze the mineral composition, characteristic of infrared spectra, color genesis, and characteristic of micro- morphology of these stones. The results of the study indicate that the mineral compositions are different between these stones. The analysis of IR and XRD studies indicate that the black Kengtou stone is mainly composed of dickite. On the other hand, XRD analysis indicates that it can contain a small amount of pyrophyllite, illite, pyrite, and quartz. However, the analysis of IR and XRD studies indicate that black Tianhuang stone is mainly composed of dickite or nacrite. On the other hand, XRD analysis indicates that the minor mineral composition in the black Kengtou stone can be svanbergite and tochilinite. Their characteristics of micro-morphology of black Tianhuang stone and black Kengtou stone are also different. The crystal size of dickite in black Tianhuang stone is inconformity, and the margin of lamellae crystals is smoothed. It indicates that such kind of stone had undergone corrosion effect due to water-rock reaction. On the other hand, the black Kengtou stone are well crystalized. The lamellae has sharp margin, and the size of the lamellae is relatively uniform. It indicates that the black Kengtou stone is original ore. According to the trace chemical composition analysis of LA-ICP-MS, it preliminary suggests that black color of both black Tianhuang and Kengtou stones have relationship with Fe element. The final conclusion of color genesis needs more experiments to prove.

[Mineralogical and spectral characteristics of copper pectolite].

Copper pectolite, a type of pectolite with blue stripes, is a rare gem material with a great market prospect. Mineralogy and genesis were investigated using X-ray diffraction (XRD), Fourier infrared absorption spectroscopy (FTIR), Raman spectroscopy (Raman), scanning electron microscopes (SEM) and ultraviolet-visible spectrometer(UV-VIS) to understand the mineralogical compositions and characteristics of the parts with different color. XRD, FTIR and Raman result showed that copper pectolite is composed of pectolite and minor calcite, consistent with the result of SEM. FTIR showed that an obvious band at 1 500 cm(-1) with 883 and 710 cm(-1) occurred on the white part that contain minor calcite, while the band was absent on the blue part. UV-Vis absorption spectroscopy analysis showed that the blue part has 640 nm absorption band in the UV area that indicates containing elements Cu. The different mineralogical compositions of the white and blue part indicate their different geological conditions.

[Gemology and spectra characterization of gem garnet from Muling City, Heilongjiang Province].

Cenozoic basalts gem-garnets from Muling City, Heilongjiang Province were studied by using standard gemological methods, electron microprobe, Raman spectroscopy, infrared spectroscopy, and ultraviolet-visible spectroscopy to obtain the gemology and spectra characterization. Chemical composition analysis indicates that the garnets are pyropes with some impurity element Fe, Ca, Mn, Cr, and Ti. The average chemical structure formula of the gem-garnet is (Mn0.022 Ca0.455, Fe(2+)0.720, Mg1.793) sigma = 2.990 (Ti0.003 Cr0.009 Fe(3+)0.062 Al1.951) sigma = 2.025 (SiO4)3. Roman spectrum analysis suggests that there are mixed-phases in the garnet, which can be shown by the Roman shift which is caused by bridging oxygen vibration of garnet. The Roman shifts of bridging oxygen bending vibration of pyrope are at 560 cm(-1) (A(1g)), and 641 cm(-1) (E(g) + F(2g)), while the Roman shifts of bridging oxygen bending vibration caused by E(g) + F(2g) of almandine and grossular are at 507 and 486 cm(-1). IR functional group area indicates that the pyropes have no molecules water, but seldom pyropes have a little structure water, which forms three stepped weak absorption peaks at 3 585, 3 566 and 3 544 cm(-1) respectively. Most pyropes are brown-red, which is caused by electronic transitions of impurity ions Cr3+, Fe3+ and Mn2+. UV-Vis spectra show that absorption peaks caused by electron transition of Fe3+ are at 570, 521 and 502 nm, while absorption peaks caused by electron transition of Mn2+ are at 460 and 430 nm, and absorption peaks caused by electron transition of Cr3+ are at 690 and 367 nm.

[Infrared and Raman spectra study on Tianhuang].

The Tianhuang stones, from Shoushan in China, were studied by using X-ray powder diffractometry (XRD), infrared (IR) spectroscopy and Raman spectroscopy to obtain the spectra characterization. Wave numbers 3621, 3629 and 3631 cm(-1) in the IR spectra and 3626, 3627 and 3632 cm(-1) in the Raman spectra are the characteristic peaks of dickitic Tianhuang, nacritic Tianhuang and illitic Tianhuang, respectively. Raman spectra assigned to OH are in good agreement with the IR results at 3550 -3750 cm(-1). Dickitic Tianhuang includes ordered dickite and disordered dickite. Compared with ordered dickite, the band assigned to OH3 of disordered dickite shifts to low-frequency by 8 cm(-1) and the relative intensity becomes stronger. The disorder structure may relate to the high level of Fe. The IR absorption spectra of nacritic Tianhuang superimposes strong peaks of dickite, indicating that IR absorption bands of dickite are stronger than that of nacrite at 3550-3750 cm(-1). The main mineral composition of illitic Tianhuang is 2M(1), while illite Tianhuang contains a small amount of 1M. All these characters provide a theoretical basis for the scientific identification of Tianhuang.