Ianthinite: A rare hydrous uranium oxide mineral from Akkavaram, Andhra Pradesh, India

Journal of Earth system science

P V Ramesh Babu1¹  Yamuna Singh1¹  S K Srivastava1¹  K K Parashar1¹  R Viswanathan1¹  P S Parihar1¹ 

[1] Department of Atomic Energy, Atomic Minerals Directorate for Exploration and Research, Begumpet, Hyderabad 500 016, India.$$

关键词: Mineralogy;    ianthinite;    Akkavaram;    Andhra Pradesh;    India;    paragenesis.;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

Ianthinite is the only known uranyl oxide hydrate mineral that contains both U6+ and U4+. For the first time, we report ianthinite from India (at Akkavaram, Andhra Pradesh), which is hosted in basement granitoids. The mineral occurs in the form of tiny grains, encrustations and coatings in intimate association with uraninite and uranophane. X-ray diffraction (XRD) data reveals that d-spacings of the investigated ianthinite are in close agreement with the corresponding values given for ianthinite standard in International Centre for Diffraction Data (ICDD) card no. 12-272. The crystallographic parameters of the studied ianthinite are: ao = 11.3 (1) Ã…, bo = 7.19 (3) Ã… and co = 30.46 (8) Ã…, with a unit cell volume of 2474 (27) Ã…3. The association of investigated ianthinite with uraninite suggests that the former has formed due to oxidation of the latter. Since a major part of the uraninite was exposed to oxidizing meteoric water, much of it has been transformed into hydrous uranium oxide (ianthinite) and very little part remained unaltered as uranium oxide (uraninite). Absence of schoepite in the investigated ianthinite suggests that after its formation it (ianthinite) was not exposed to oxygen/oxidizing meteoric water. As the oxidation was partial and short lived, some amount of primary uraninite is also preserved.

【 授权许可】

Unknown