Vibrational spectra of the hydrated carbonate minerals ikaite, monohydrocalcite, lansfordite and nesquehonite

The Raman (200-4000 cm(-1)) and infrared (600-4000 cm(-1)) spectra of four rare carbonate hydrate minerals are reported. These are naturally occurring and synthetic ikaite CaCO3.6H(2)O, and nesquehonite MgCO3.3H(2)O; natural monohydrocalcite (CaCO3H2O)-H-., and synthetic lansfordite MgCO3.5H(2)O. The spectra of synthetic ikaite partially substituted with (H2O)-H-2 and also with C-13 were measured, as were those of synthetic deuteriated nesquehonite. Spectra of ikaite and lansfordite, both of which decompose at room temperatures, were measured below 0 degreesC. Assignments of fundamental modes are proposed. (C) 2003 Elsevier B.V. All rights reserved.