Characterization of natural silicate garnets by means of non-destructive testing methods

Abstract

Two kinds of natural silicate garnets from the known origin countries were investigated: pyralspites – pyrope (Russia), almandine (India), rhodolite (India), spessartine (India), blue colour-change garnet (Sri Lanka), and ugrandites – andradite (Russia), demantoid (Russia), topazolite (Russia), rainbow garnet (Japan), grossular (Kenya-Tanzania), colourless grossular (India), light orange grossular (India), dark green tsavorite (Tanzania), medium green tsavorite (Kenya), light green tsavorite (Kenya), orange hessonite (Sri Lanka), pink hessonite (Sri Lanka), cinnamon hessonite (India) and uvarovite (Russia). The chemical composition of the garnets was performed with a scanning electron microscope. The physical properties such as specific gravity and refractive index were measured for the majority of garnets investigated. The spectroscopic meth­ods – visible light absorption spectrophotometry, Raman spectroscopy and cathodoluminiscence microscopy – were applied for the characterization of the mentioned natural silicate garnets.