【摘要】 斜硅石(moganite)是1999年才在国际上被正式承认为二氧化硅的新矿物种类,科学家们对其的研究还不深入。本文综述了斜硅石的晶体结构、高温热力学行为、物理化学性质以及理论计算的研究现状。同时,结合当前研究进展,讨论了斜硅石研究中亟待解决的关键科学问题,并且阐述了斜硅石研究的重大科学意义。斜硅石广泛存在于石英共生矿物中,目前纯相斜硅石还没有被发现。斜硅石有较高的含水量(约2%~4%),主要以自由水和羟基的形式存在,特别地,羟基以缺陷的形式存在于斜硅石晶格中。在高温热行为方面,斜硅石在570 K发生I2/a—Imab的可逆结构相变,类似石英中由软模驱动的α-β位移型相变,然而,由于目前缺少直接的实验证据支撑,其相变机理仍悬而未决,对于斜硅石在二氧化硅相图中的位置仍不明确。地质学上,斜硅石被认为是矿物在蒸发环境下结晶的证据,在成岩过程中具有十分重要的作用。尽管斜硅石在众多二氧化硅矿物中均被发现,但对于斜硅石在其结构演化中的关键作用仍不清楚,认识斜硅石在这些地质过程中的科学价值,需要了解其高温、高压特性和稳定性,而该方面的研究有待深入开展。更多还原

【Abstract】 Moganite is a polymorph of microcrystalline silica which was approved as a distinct and valid mineral species in 1999 by International Mineralogical Association’s Commission on New Minerals and Mineral Names. This paper briefly reviewed the structure, thermal dynamics, physical and chemical properties and computer simulation of moganite. In addition unsolved issues in moganite were discussed and the scientific significance of the study on moganite was elaborated. Moganite was found to commonly coexist with varieties of microcrystalline quartz in evaporite and hydrothermal environments. High content H species were found in moganite existing in the form of free water andhydroxyl（ about 2%-4wt%）,and the hydroxyl existed in the form of defect. Moganite has quite different physical properties comparing with other SiO₂ polymorphs. It has recently been found that moganite undergoes a structural phase transition from space group I2/a to Imab at the temperature of570 K.The transition is proposed to be displacive and associated with soft modes,like the α-β phase transition in quartz. However,the transition mechanism is not fully consistent with the available experimental data. Whether moganite has a place in the phase diagram of SiO₂ remains unknown. In aspects of geology,moganite is considered as an indicator of evaporitic regimes,which may plays an important role in the diagenesis. However,researches on the role moganite plays in minerals are still in primary stage. Though,moganite has been found in many SiO₂-bearing minerals,and understandings of the role of moganite in minerals are competing. Gaining a better understanding of thermal dynamics and stability of moganite would be important for evaluating its role in geology process. However,these physical properties of moganite remain poorly studied.更多还原