## 4 The Example of the Green Stones
### The Fourier Transform InfraRed Spectroscopy (FTIR) Investigation
The IR main bands of the pure actinolite and tremolite phases, along with nephrite, antigorite, lizardite, and chrysotile phases, along with serpentine, have been reported as references for completeness. can be acquired by this method, though unfortunately this procedure shows some limits in cultural heritage or gemology studies. These limits can be partially bypassed: in recent decades, several accessories and/or modules have been developed to solve the problems correlated to the sample's preparations (i.e., integration spheres, Attenuated Total Reflectance--ATR, etc.). All of these accessories are mandatory in gemological and cultural heritage applications. As discussed above, using this set-up, the FTIR characterization can also be performed without any sample preparation on opaque materials, being extremely useful for poly-phases and uneven samples such as Green Stones. Unfortunately, although very useful, micro-FTIR is not a portable system. On the other hand, the special affinities of the IR source with organic compounds make FTIR spectroscopy particular suitable to identify jade impregnation by organic substances treatments (Figure 9) [70, 155, 156]. As reported by [PERSON] [156], it is interesting to note that in this modality, none of the fingerprint bands correlated with the most characteristic vibrational modes of the jadeite are detectable, due to detector saturation, while the presence of an extraneous compound such as resin, wax, or oil can be easily highlighted. Since antiquity, the application of oil or waxes has been well-known to preserve porous gemstone materials, including jades. Since the 1980s, the impregnation treatment using artificial epoxy resins has been developed and quick diffused, due to its higher durability. In Green Stones modern trade, the so-called \"bleaching\" treatment applied especially on jadeite-jade is very common. Using this two-step treatment, less attractive brownish-grayish jadeite can become whiter, by virtue of removing impurities (causing the brown and gray colors) by a chemical attack process, followed by a deep polymeric (epoxy resins) impregnation [155, 156, 157]. This procedure originates the \"type B\" jade [84]. Although this treatment is not common in cultural heritage or archaeological samples, substances such as oil, wax, and other materials may be used by conservators to protect the surface of an object instead of the previously used varnishes [55]. Therefore, care must be taken to determine if it is a treatment or only a conservation measure of the gems [85]. For  
Figure 9: IR absorption spectra of two Jadeite samples: jadeite with traces of surface waxing or oiling, which can be typically correlated with polishing and cutting operation, is reported in red [156], while the black line characterizes jadeite impregnated with epoxy resin [155, 156]. The range between 2500 and 3300 cm\({}^{-1}\) is the most suitable for organic compound impregnation treatments detection, due to the strong absorptions correlated with the CH stretching vibrational modes [155, 156]. Spectra have been acquired by Frontier FTIR spectroscopy, PerkinElmer, equipped with Harrick reflection sphere, and analyzed with Spectrum Software. Data: [PERSON], GECI. all these reasons, when analyzing Green Stones, taking into account current treatments can complete the characterization of the samples. Thus, Raman and FTIR spectroscopies can be considered as complementary techniques.