Raman and LIBS Analysis of Garnet Species
Earlier this year, we had the opportunity to analyze an extensive sampling of garnets from around the world, courtesy of collections from Dan Zellner of DanZ Rockshop and Nathan Robey, Sales Application Engineer at Avantes. In our first application note titled, “Characterization and Identification of Garnet Using Spectroscopy Techniques,” we focused on a specific garnet species known as spessartine. We examined differences in color (reflection), absorption (transmission), and molecular structure (Raman), which highlighted the differences between spessartine garnets from the Fujian Province of China, Minas Gerais, Brazil, and the Federally Administrated Tribal Areas (F.A.T.A.) of Pakistan. However, we were still left with several unanswered questions about the nature of these differences. For example, why was the sample from Pakistan less absorbent in the near-infrared than the other samples? Why was the stone from Brazil a deep red color, while the other two appeared to be more amber? What caused the slight differences in the Raman spectra of all three? As a result, we have decided to revisit our initial analysis with a twofold goal; expanding the Raman analysis to include additional garnet species and performing LIBS analysis to gain insight into the atomic differences between the different stones.