Abstract
Twenty-two andradite samples from a variety of geological environments and two synthetic hydroandradite samples were studied by Fourier transform IR spectroscopy. Their spectra show that H enters andradite in the form of OH-. Amounts up to 6 wt% H2O occur in these samples; those from low-temperature formations contain the most OH-. Some features in the absorption spectra indicate the hydrogamet substitution (SiO4)4-↔(O4H4)4- whereas others indicate additional types of OH- incorporation. The complexity of the spectra due to multi-site distribution of OH- increases with increasing complexity of the garnet composition.
Received: 1996-8-1
Accepted: 1998-2-4
Published Online: 2015-11-13
Published in Print: 1998-7-1
© 2015 by Walter de Gruyter Berlin/Boston