Tsavorite and other Grossulars from Itrafo, Madagascar

Abstract

Since 2002, tsavorite and other grossular varieties have been recovered from a primary deposit at Itrafo, a village in the Andrembesoa area of central Madagascar. Twenty-two samples from this locality were investigated by classical gemological methods, chemical analysis, and UV-Vis-NIR and mid-IR spectroscopy. The garnets' chemical composition was nearly pure grossular (>92 mol.%), with iron and vanadium as the main chromophores. Their iron content and Fe 2 O 3 :V 2 O 3 ratio were higher than those generally found in tsavorite from well-known deposits. Although the Itrafo deposit is relatively large, and new veins could be discovered, future production will be limited by access difficulties and security concerns. © 2012 Gemological Institute of America.