Publication Date:
2013-02-13
Description:
The occurrence of vorlanite, cubic CaUO 4 , is reported in the Nopal I uranium deposit (Sierra Peña Blanca, Mexico). This is the first time this rare calcium uranate has been found displaying a cubic morphology, in agreement with its crystal structure. Vorlanite occurs as nanoscale crystals embedded in U-bearing opal, with a Ca/U ratio of ~1. Association with opal suggests that vorlanite formed at Nopal during late-stage U-mobilization under oxidizing conditions and low (〈50°C) temperature. The presence of nanoscale uranate crystals in an environment largely dominated by uranyl silicates indicates that uranates may play a role in uranium scavenging at low temperature. In addition, the occurrence of vorlanite in the crystal shape consistent with its structure provides unique information on its conditions of formation.
Print ISSN:
0003-004X
Electronic ISSN:
1945-3027
Topics:
Geosciences
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