The characterization of natural gemstones using non-invasive FT-IR spectroscopy: New data on tourmalines

Talanta. 2018 Feb 1:178:147-159. doi: 10.1016/j.talanta.2017.09.030. Epub 2017 Sep 11.

Abstract

Fourteen samples of tourmaline from the Real Museo Mineralogico of Federico II University (Naples) have been characterized through multi-methodological investigations (EMPA-WDS, SEM-EDS, LA-ICP-MS, and FT-IR spectroscopy). The samples show different size, morphology and color, and are often associated with other minerals. Data on major and minor elements allowed to identify and classify tourmalines as follows: elbaites, tsilaisite, schorl, dravites, uvites and rossmanite. Non-invasive, non-destructive FT-IR and in-situ analyses were carried out on the same samples to validate this chemically-based identification and classification. The results of this research show that a complete characterization of this mineral species, usually time-consuming and expensive, can be successfully achieved through non-destructive FT-IR technique, thus representing a reliable tool for a fast classification extremely useful to plan further analytical strategies, as well as to support gemological appraisals.

Keywords: External reflectance; FT-IR; Fingerprint region; Natural gemstones; Non-destructive technique; Tourmaline.