A note on the molecular water content in uranyl carbonate mineral andersonite

Abstract

The crystal structure of andersonite from Jáchymov (western Bohemia, Czech Republic) was refined from single-crystal X‑ray diffraction data to an R = 0.0286 against 1657 unique observed reflections. Andersonite from Jáchymov is trigonal, (Formula presented), with a = 17.8589(6), c = 23.6935(8), V = 6544.4(4) Å3 and Z = 18. The structural formula derived from the refinement of X-ray data is Na2Ca[(UO2)(CO3)3](H2O)5.28. This formula confirms previous structure determination on synthetic material. The maximal H2O content in andersonite is discussed also with regard to the published thermal analysis and vibration spectroscopy studies and disunities in chemical formula of andersonite in the literature.