Information-based parameters of structural complexity for two polymorphs of Ca[(UO2)2(SiO3OH)2] · 5H2O, uranophane and uranophane-β, were calculated in order to assess the impact of the structural complexity on their stability and formation. Calculations proved that uranophane-β is far more complex (IG,total = 691.90 bits/cell) than uranophane (IG,total = 345.95 bits/cell), which indirectly suggests that uranophane may form as a metastable phase during crystallization process. This suggestion is further supported by the lower density of uranophane (3.834 g/cm3) compared to that of uranophane-β (3.983 g/cm3). The hypothesis of a metastable character of uranophane is in agreement with Goldsmith's simplexity principle and the Ostwald–Volmer rule and is well supported by the frequency of occurrences of both dimorphic minerals in Nature.

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