Supramolecular crystals, photon crystals, noble opals: synthesis; genesis; search-criteria of deposits

There are a lot of papers devoted to regular dispersed structures in mineralogy, colloidal chemistry and biosystems. Some researchers (R.Iler, R.T.Greer) assume that they are formed as a result of peculiar crystallization. However, systematic studies of crystallization process (kinetics, mechanisms, consideration of acting forces, the dependence of the process on various outer parameters, etc.) have not been conducted. The proposed papers close this gap and open a new line of scientific investigation: the study of regularities of supramolecular crystallization (infracrystallization, in other words). Colloidal or supramolecular crystals are a result of this crystallization. Our investigations devoted to the synthesis of noble opal initiate this trend. Since the moment when it becomes evident that the formation of the noble opal regular structures is a result of one of the variations of crystallization, including sedimentation of silica monodispersed spherical particles, the studies become of physico-chemical character. In this case monodispersed system of amorphous silica turns to be a convenient general model to solve all theoretical and experimental problems of supramolecular crystallization. These results (articles) are presented in chronological order and they are of great importance both for mineralogy (synthesis of noble opal, genesis of colloidal minerals) and for colloidal chemistry (regularities of formation of periodic colloidal structures, study of thixotroty, physico-chemical mechanics of gels). In total they represent theoretical and experimental basis for qualitative transition from regular structures of noble opal to photon crystals of sufficient size with a minimum of inner structural defects. Chemical characteristic of our synthetic noble opal: Chemical composition – SiO2·nH2O The content of fixed water – 1,5–2% Carbon content (in black opals) – to 2% Hardness (Mohs' scale) – 5,5–6 Density – 2,0–2,3 Porosity – 1,5–2% Transparent – semi-transparent, dull Only the published scientific results are presented in the site; as the papers are published, it will be supplemented by new data. These results are of great technological importance, they make it possible to obtain an artificial noble opal, similar to natural stone, to synthesize infracrystalline mesoporous materials and in the nearest future to grow photon crystals from amorphous silica spherical particles on the basis of volumetric three-dimensional matrix. But the available technological solutions are not presented in the site*. Concrete suggestions on prospecting of local mineralization of noble opal in the promising regions of the Australian desert are the exceptions. They are given in the paper “Genesis and prospecting criteria of noble opal deposits”. Scientific researches are carried out at the Institute of Mineralogy and Petrography* of Siberian Branch of Russian Academy of Sciences, Fluid Inclusion Laboratory, scientific group of supramolecular crystallization. This work was financially supported by the Russian Foundation for Basic research (Grant 00-05-65315). Our address: Novosibirsk, Russia, 630090, Academician Koptjug Avenue, 3a. *Technological studies are not conducted at the Institute.