Vorlanite, cubic CaUO4 heated at temperatures above 750 °C, transforms irreversibly into rhombohedral CaUO4, proving that the latter crystallized as a precursor of vorlanite in high-temperature skarns. Vorlanite most probably originated due to pseudomorphic transformation of rhombohedral CaUO4, caused by disordering of cations and uranyl-bonds that resulted from α-decay events of uranium. The ease of the transition from rhombohedral CaUO4 to vorlanite and the fast reversal transition during heating can be explained by the similarity of both structures. Formation of vorlanite prevents CaUO4 from undergoing metamictization.

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