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Duan W.,CAS Institute of Geology and Geophysics | Cai B.,National Research Center for Geoanalysis | Tan M.,CAS Institute of Geology and Geophysics | Liu H.,Kunming University | Zhang Y.,National Gems and Jewelry Technology Administrative Center
Boreas | Year: 2012

Stalagmites from Xianren Cave in Yunnan Province, SW China have visible bands of alternating compact and porous sub-layers, which have recently been demonstrated to be annual: the compact sub-layer consists of elongated columnar aragonites with a general longitudinal orientation (parallel to the vertical growth axis), while the porous sub-layer is composed mainly of needle aragonites forming radiating masses. In order to understand the growth mechanism of this type of stalagmite laminae, factors that could determine the growth rate and crystal structures of modern carbonates, such as cave-air temperature, CO 2 concentration, drip rate and the hydrochemical parameters of drip water, have been monitored systematically. In this study, we selected five active drip sites to monitor for two years at a monthly frequency. Based on the monitoring results and the analyses of stalagmite laminae, we conclude that the compact sub-layer forms in winter, when the drip rate is moderate and the degassing is slow, continuous and prolonged. The porous sub-layer forms in early spring, when the drip rate is lower and Mg/Ca is higher than that during the formation of the compact sub-layer. We also found exceptionally some calcite laminae. Furthermore, we discovered modern calcites precipitating at all study sites in the first hydrologic year when the rainfall was very abundant. Therefore, it is suggested that the occurrence of localized calcites in an aragonitic stalagmite indicates an interval of higher rainfall. © 2011 The Authors. Boreas © 2011 The Boreas Collegium.


Liu Y.,Liu Research Labs | Lu T.,National Gems and Jewelry Technology Administrative Center | Mu T.,National Gems and Jewelry Technology Administrative Center | Chen H.,National Gems and Jewelry Technology Administrative Center | Ke J.,National Gems and Jewelry Technology Administrative Center
Color Research and Application | Year: 2013

The impurity transition element chromium Cr3+ in ruby can be excited to high energy levels by absorbing visible light. When the excited Cr3+ returns to ground state through an intermediate energy level, the ruby emits red light as fluorescence. The fluorescence of ruby is actually caused by visible light, not by ultraviolet. The color of ruby is attributed to both the absorption and the fluorescence. The spectrum of a natural ruby under visible light is directly measured by a dual integrating sphere spectrometer. The measured spectrum includes both the spectral reflectance and the fluorescence caused by visible light. This study confirmed that the red fluorescence of ruby is indeed caused by visible light, not by ultraviolet radiation. In addition, average color of the ruby is calculated from the measured spectrum, and true color grade is also obtained by the artificial intelligent software of the spectrometer. © 2012 Wiley Periodicals, Inc. Col Res Appl, 38, 328-333, 2013 Copyright © 2012 Wiley Periodicals, Inc.


Chen X.,China University of Geosciences | Chen X.,National Gems and Jewelry Technology Administrative Center | Chen H.,National Gems and Jewelry Technology Administrative Center | Lu T.,National Gems and Jewelry Technology Administrative Center | He M.,China University of Geosciences
Key Engineering Materials | Year: 2016

Emerald is the green to greenish blue variety of beryl, which contains chromophore chrome and vanadium. Emeralds of all deposits have fissures, so most have been filled to avoid fragmentation during cutting. Stability is an important factor to filling emeralds. Recently, a new filler ExCel occurred, which is considered stable and removable, however, its durability is lack of scientific basis and testing. This study used magnification, fluorescence technology, FTIR and UV-Vis spectroscopy to investigate the durability of ExCel-filled emeralds. Emeralds filled with ExCel are relatively stable under conditions of daily wear in general, but durability decreased in hydrochloric acid, acetone or under heating to over 200°C. Fractures were more evident in side of emerald after hydrochloric acid immersion. After soaking in acetone fissures increased and deepened significantly. After heating to 250°C, brown material leaked from fissures of ExCel-filled emeralds, analyzed to be bisphenol A epoxy resin, imine curing agent and diluent components. The study has indicative significance for suitable conditions of ExCel-filled emerald wearing and preservation. © 2016 Trans Tech Publications, Switzerland.


Feng X.-Y.,National Gemstone Testing Center | Lu T.-J.,National Gems and Jewelry Technology Administrative Center | Zhang H.,Yunnan Land and Resources Vocational College | Zhang Y.,National Gems and Jewelry Technology Administrative Center | Zhang J.,National Gemstone Testing Center
Kuangwu Yanshi/ Journal of Mineralogy and Petrology | Year: 2015

Nephrites from Xinjiang, Qinghai, Taiwan and so on were studied by using Raman spectroscopic. Specifically, a variety of nephrite with different colors, such as Baiyu, Qingyu, Huangyu and Biyu were investigated over their cations at M] and M3 sites. Raman spectra in the fingerprint region showed that the main composition of nephrite is tremolite. The replacement of impurity ions leads to some nuances in the chemical composition for a variety of nephrite with different colors. The peak of M-OH stretching vibration is important for recognizing the main chemical composition of nephrite as well as its color categorization. Ratio of Mg2+/ (Mg2+ + Fe2+) were calculated by using peak intensity ratio of 3 675 cm-1 ,3 661 cm-1,3 645 cm-1 ,and the relative content of Fe,Mg element was tested by using X-ray fluorescence and electron probe. The reliability tested by using EDXRF and electron probe indicated that the method of peak intensity ratio of 3 675 cm-1,3 661 cm-1 ,3 645 cm-1 can be used as a reference for evaluating nephrite whiteness.


Lu T.,National Gems and Jewelry Technology Administrative Center | Chen H.,National Gems and Jewelry Technology Administrative Center | Qiu Z.,Sun Yat Sen University | Zhang J.,National Gems and Jewelry Technology Administrative Center | And 5 more authors.
European Journal of Mineralogy | Year: 2012

Diamond crystals from the Shandong and Liaoning kimberlites, China, display a distinct "seed-like" multiple core growth structure with multi-stage growth history. Cathodoluminescence and DiamondView images revealed that the core portion of the diamonds is occupied by a "seed-like" precipitated or smaller core which could be a resorbed early crystal formed by a cuboid growth mechanism. At the boundary between the core portion and the octahedral layers, the nitrogen concentration drops abruptly to ∼1 ppm from a few hundreds of ppm in the core portion, suggesting a fundamental change in geochemical growth environments in the mantle. This is associated with a switch in zoning trends in δ 13C from outward increasing to outward decreasing values, confirming that a change in growth conditions occurred. © 2012 E. Schweizerbart'sche Verlagsbuchhandlung, D-70176 Stuttgart.

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