The Occurrence State Of Organic Matter In Gem-quality Red Coral And The Bleaching Experiment

Gem-quality red coral is one of the most important organic gems formed by biomineralization. Its main ingredient is inorganic mineral calcite. Besides, there is a small amount of organic matters. The organic component in the gem-quality red coral is less, but the position it occupied in the structure and composition cannot be ignored. In this paper, we have experimentally tested and researched the occurrence state of organic in gem-quality red coral in multi-aspect and multi-scale. What’s more, we explored the bleaching experiment to remove the organic matter in gem-quality red coral, which reveals the occurrence of organic matter in red coral reversely.The occurrence state of organic matter in gem-quality red coral mainly includes two aspects. One is the distribution of organic matter in the structure of red coral, and the other is the composition of organic matter in red coral.The position of organic matter in the gem-quality red coral is mainly researched according to the structure observation of the red coral, and then to determine the distribution of organic matter in the structure. In this paper, we have studied the structure of the red coral in the multi-scale from macro to micro and then to nano-scale and analyzed the occurrence, shape, distribution and effect of organic matter in the structure. Specific as follows:1. In the research of location of organic matter in the macro-structure of the gem-quality red coral, firstly, through the analysis of previous material on coral living branch, we have found that organic compounds widely present in living tissue of red coral. Then, by observing the unprocessed branch body by the naked eye and microscope, we have found that numerous remaining dry tissues and organic matter exist on the surface of red coral. These organisms are important components of red coral in vivo, and the part of biological function.2. In the research of the occurrence of organic matter in the gem-quality red coral from microscopic scale, we have done the microscopic observation of the polarizing filter, coloring experiments of organic reagents and bleaching experiments of injured organic, and have found that organic matter presents as layered distribution in the growth and between the growths of the axial skeleton in red coral. These organisms are the manifestation of cyclical growth of the red coral and caused red coral into the organic-inorganic composite in a macro perspective. In addition, under the scanning electron microscope, in the spicules we have observed the organic compounds which take part in the bone needles layered structure or link spicules, in calcite layer we have found the interlayer organic matter, and in abnormal growth area we have observed the immethodical secretive organic matter. These organisms are important components in the regulation growth of axial skeleton in red coral, microstructure formation and calcite distribution.3. In nano-scale, Organic matter in the gem-quality red coral presents in the calcite grains and calcite crystals and between grains. Using transmission electron microscopy to observe the nano--structure of the red coral, we have found not only the calcite lattice, but also the most microscale organic in the red coral. Intercrystalline organic matter usually was like of mosaic in the gap between the crystal and the crystal; intragranular organic matter was like of inclusions in the calcite crystal, which can be filled into the area of clutter nano-domain in crystal. Intercrystalline organic matte plays a significant role in controlling the size of calcite crystals intragranular organic matter is one of the calcite crystal structure, which achieve the assembly of nanostructures in calcite crystal.To study the constituents of the organic matter in the gem-quality red coral, firstly, we have demineralized the red coral to dissolve inorganic calcite, and then centrifuged the resulting solution to enrich the water-insoluble part in organic matter of which the color is orange red. After that we have done the spectral test by Raman and IR spectra to the enriched organic matter, and found part of functional groups in the gem-quality red coral organic:C-C, C=C, alkyl, C=O and C-O. What’s more important in the test of the occurrence composition of organic matter in the gem-quality red coral, we carried out experiments by gas chromatography-mass spectrometry (GC-MS) test which is an important test in the constituents’tests of the organic matter. We use accelerated solvent extraction method to extract the organic matter in the red coral, then choose the column chromatography to separate the organic hydrocarbon and non-hydrocarbon components, respectively. Finally, mass spectrometry is used to test the two components. The test results show various organic constituents in gem-quality red coral such as alkanes, alcohols, acids, steroids, and olefin.The experimental program of pearl bleaching experiment is used to bleach the gem-quality red coral tentatively. Firstly, we use hydrogen peroxide in bleaching agent to corrode the organic matter in the red coral, which can observe the structural damage of the red coral. The results reversely prove the location of the occurrence of organic matter in the red coral. Secondly, it has the significance of optimization, which can optimize darker colors, red and black red coral color to improve the value. Then by analyzing the results of bleaching experiments, it can be verified that the albefaction of red coral reveals the significance of organic matter to the red coral; in addition, the new form crystal formation show the reaction of organic to biomineralization of red coral.In this paper, based on the studies and conclusions on the occurrence state of organic matter in the gem-quality red coral, we summed up the process mechanism of biomineralization in red coral, analyzed the effects of organic matter in the red coral biomineralization process and its influence on mechanical properties and color of red coral.A multi-level structure exists in gem-quality red coral biomineralization, and this build mode influenced by organic matter from macro to micro scale. In the nucleation of calcite, organic matter as a template, makes the calcite slowly nucleation at specific sites, when crystal grows to a certain size, organic matter limits the crystal size to make it stop growing. These oriented submicroscopic crystal units in the coupling of organic matter can form higher-level crystal unit. Intergranular organic matter and organic matter between layers constitute the framework of the three-dimensional space, so that the calcite crystal unit accumulates in them, and form the micro-structure. Microstructure can be used as a growth center. And the organic regulate calcite around the growth center to accumulate and of form macroscopic spheres. Due to seasonal growth, organic matter circle mixes between the growth of the spheres and the growth of spheres, which makes red coral mineralization process from the microscopic to macroscopic complete implementation.Superior mechanical properties of gem-quality red coral, higher than the hardness of the mineral calcite and good toughness, are due to the composite structure formed by the participation of organic matter in the red coral. Organic matter participates in the crystal structure from the nano-scale, strictly controls the size of the crystal, fine builds a multi-level structure, and achieves the organic-inorganic compound in every scale, which thereby increases the hardness and enhances toughness. Demineralisation of enriched orange-red organic and bleaching experiments can verify that the charming red of gem-quality red coral is closely related with the organic compounds in structure.All in all, the organic matter exists in gem-quality red coral from macro to micro and to nano-scale, and its main functional groups and some components has also been proven; bleaching experiments also show significance in explaining the occurrence of organic matter. What’s more, according to the occurrence state of organic matter in gem-quality red coral, we summarized the effects of organic matter in the red coral biomineralization, and analyzed the excellent mechanical properties and color of red coral due to organic matter.