- journal_title：American Mineralogist
- Contributor：Guillaume Othmane ; Thierry Allard ; Nicolas Menguy ; Guillaume Morin ; Imène Esteve ; Mostafa Fayek ; Georges Calas
- Publisher：Mineralogical Society of America
- Date：2013-02-01
- Format：text/html
- Language：en
- Identifier：10.2138/am.2013.4295
- journal_abbrev：American Mineralogist
- issn：0003-004X
- volume：98
- issue：2-3
- firstpage：518
- section：Actinides in Geology, Energy, and the Environment†
The occurrence of vorlanite, cubic CaUO4, 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.