A review of the models proffered to advance the notion of the metastability of illite shows that these models are not supported by the various data groups that have become available. Given that clay minerals are products of water–rock interactions, low-temperature hydrothermal experiments provide singular insights into their relative stabilities; such experiments with natural materials of contrasting pedigree (illites, sericites, muscovites, and chlorites) show that clay-mineral behaviors in low-temperature hydrothermal solutions are amenable to equilibrium thermodynamic conventions. The data from hydrothermal experiments coupled with data from geothermal fields indicate that muscovite is not a stable phase in the P-T-X range in which authigenic illite occurs; given that experimental data and field occurrence suggest that muscovite and illite have different P-T stability regimes, the continued use of muscovite as a proxy for illite in thermodynamic models is of questionable utility. Furthermore, morphometric studies of clays undergoing illitization show that crystal-size distributions exhibit log-normal patterns. Because log-normal distributions derive from maximum entropy effects, these crystal-size distributions may reflect the effects of entropy production during crystallization rather than kinetically driven Ostwald ripening of illitic phases; the small crystal size of clay minerals may derive from constraints imposed by the physicochemical conditions of their environments of formation. Presumably, irreversible thermodynamics provides the framework for a quantitative understanding of the evolution of complex clay minerals in space and time.

中文翻译：

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伊利石和矿物的热力学稳定性

对用于推进伊利石亚稳定性概念的模型的回顾表明，这些模型不受已获得的各种数据组的支持。鉴于粘土矿物是水-岩相互作用的产物，低温热液实验提供了对其相对稳定性的独特见解；使用具有对比谱系的天然材料（伊利石、绢云母、白云母和绿泥石）进行的此类实验表明，低温热液溶液中的粘土矿物行为符合平衡热力学约定。热液实验数据和地热田数据表明，白云母不是自生伊利石出现的 PTX 范围内的稳定相；鉴于实验数据和现场发生表明白云石和伊利石具有不同的 PT 稳定性体系，在热力学模型中继续使用白云石作为伊利石的替代品是有问题的。此外，对经历伊利特化的粘土的形态测量研究表明，晶体尺寸分布呈现对数正态模式。因为对数正态分布源自最大熵效应，这些晶体尺寸分布可能反映了结晶过程中熵产生的影响，而不是动力驱动的伊利石相 Ostwald 成熟；粘土矿物的小晶体尺寸可能源于其形成环境的物理化学条件所施加的限制。想必，