| Mengyin of Shandong province is one of the important diamond producing areas in our country. Its original mineral has a high-grade and large reserves but quality is poor, mainly industrial diamond. The mineralogical studying of diamonds from Shandong Mengyin can guide the diamond modification on experiments, improve its quality, increase the economic benefits of diamonds and improve the utilization of diamond resources.A series of researches on the original stone and the sliced sample have been used in this article,such as micro-observation, spectroscopic (infrared absorption spectrum test, Raman spectrum test, UV-visible absorption spectrum test) and luminescence (cathodoluminescence test, UV fluorescence observations) and a series of tests, in order to have a system research on characteristics of Mengyin diamond gemstones mineralogical. Mainly supported by the following understandings:1 In this paper, the 30 original stones of Mengyin diamond crystal has a relatively good shape, most of them are single-shape and ladder octahedron, part of them are even borned, poly-shaped occasionally. Samples generally are subjected to intense corrosion, primarily we can see 10 kinds of crystal surface erosion in the diamond crystal surface. Most of them have dark mineral inclusions, crystal inclusions and cracks. Samples generally have more uniform color, but in some individual original stone and slices, the color appears in the uneven distribution.2 The infrared absorption spectrum has demonstrated the intrinsic peak of diamond, the absorption peak caused by nitrogen, hydrogen (C-H bond, N-H bond, O-H bond, H2O), inclusions (olivine, pyrope, chromite, diopside, etc.). The absorption peak near 1175 cm-1 and 1010cm-1,1100cm-1 belong to absorption line B1 of polymerization nitrogen. According to characteristic of nitrogen peaks in infrared spectrum, we can see that with the deepening of diamond-brown tone, three kinds of nitrogen absorption peaks are increased, but the increases are in different magnitude. The growth of absorption peak of the pairs nitrogen is most obvious, followed by absorption peak of polymerization nitrogen, absorption peak of the segregation nitrogen in sheet is only in a certain growth in a small area. Samples are mainly typeⅠaAB dominated, followed by the typeⅠaB.3 Samples of the original stone diamond show different colors, different intensity of cathode luminescent phenomenon, which are generally regional lights, indicating that the majority samples subjected to internal stress, corrosion and other roles in the formation process,with the crystal lattice changing. Samples mainly display a blue and white, yellow green cathode luminescence, local appears purple, pink light district. Light phenomenon is obvious in corrosion part.4 UV fluorescence of samples is mainly in blue-white, yellow-white. And long-wave is stronger than the short-wave. 5 Raman spectroscopy shows the intrinsic peak of diamond, C-H bond absorption peak, N2 as well as Si-C bond absorption peak.The intrinsic peak of Raman spectra of the samples drifts to the direction of High-wave numerical, indicating that some changes of structural features of diamond have taken place.6 The overall features of UV-Vis absorption spectra of Test samples are almost the same. From 300nm to 500nm is a curve of transmittance gradual increasing. There is a 560nm broad absorption band as the center. Behind the 650nm, although the transmittance gradually increased, there are a number of wide-ranging absorption band. There are N2, N3, H3, GR1 absorption in test samples.7 Natural diamond can appear GR1 color center, and appear in the yellow-brown diamond. |
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