Spectroscopic examination of Red Queen's funerary mask and her green stone offering from the Mayan site of Palenque, Mexico.

This work presents a non-invasive material study of the Red Queen's funerary offering via in situ infrared (FTIR) and Raman spectroscopies for mineral identification, and X-ray fluorescence spectroscopy (XRF) for elemental characterization. A second non-destructive laboratory stage on the main mask of the offering only was carried out by particle induced X-ray emission (PIXE) for further elemental analysis. The main FTIR results indicate that all of the tesserae of the main mask are composed of malachite, identified by their ν(CuO), ν(CuOH), ν1-ν4(CO32-) and δ(CO32-) infrared and T(CO32-) Raman vibrational modes. Moreover, the pupils are composed of obsidian (δ(SiOSi) and ν(SiO) infrared vibrational modes), and remarkably, jadeite was identified in the sclera of the eyes. Most of the accompanying mask's tesserae are green quartz and chalcedony (δ(SiOSi) and ν(SiO) infrared and Raman vibrational modes). The pendants are made of jadeite, while the headdress´ tesserae were identified as omphacite. The diadem and necklace's green beads were mostly jadeite, omphacite and albite. Jadeite, albite and omphacite were identified through their characteristic infrared and Raman vibrational modes: ν(SiOSi), δ(SiOSi), τ(SiO4) and AlSiO4 interactions. Yellow-orange beads in the diadem and in the pectoral are quartz. Green and blue pectoral beads are jadeite, omphacite and quartz. Limestones and shells identified in the figurine, valve and in some of the headdress and accompanying mask's tesserae, were properly classified by Raman spectroscopy, using their characteristic ν1 and ν4 (CO32-) vibrational modes for aragonite and beta-carotenes characteristic Raman shifts for Spondylus valves. These results indicate a special selection and the use of unique raw materials for the royal burial of the Red Queen, different to those used for other rulers of Palenque and other contemporary Mayan sites.

Methodology for the non-destructive characterization of jadeite-jade for archaeological studies.

The present paper proposes a methodology that complies with the requirements of identifying and characterizing jadeite (and its associated minerals) for archaeological studies, avoiding the acquisition of samples and ensuring the integrity of the object. The methodology exploits a carefully selected array of techniques (optical microscopy, UV fluorescence photography, X-Ray digital radiography, infrared and Raman spectroscopies, X-Ray fluorescence and particle induced X-ray emission spectroscopies) that, despite not definitively replacing laboratory procedures, provides a first mineral and elemental evaluation of jadeite archaeological objects. The proposed methodology was applied in the characterization of twelve different jade tones, allowing the identification of major - jadeite, albite and omphacite - and minor - pumpellyite, actinolite, analcime, rutile, grossular and titanite - mineral phases. To display its advantages and limitations, this methodology was also compared with a characterization employing specific gravity measurements and with an invasive methodology based on petrography and scanning electron microscopy with energy dispersive spectroscopy.

Identification of natural red and purple dyes on textiles by Fiber-optics Reflectance Spectroscopy.

Understanding dye chemistry and dye processes is an important issue for studies of cultural heritage collections and science conservation. Fiber Optics Reflectance Spectroscopy (FORS) is a powerful technique, which allows preliminary dye identification, causing no damage or mechanical stress on the artworks subjected to analysis. Some information related to specific light scattering and absorption can be obtained in the UV-visible and infrared range (300-1400nm) and it is possible to discriminate the kind of support fiber in the near infrared region (1000-2500nm). The main spectral features of natural dye fibers samples, such as reflection maxima, inflection points and reflection minima, can be used in the differentiation of various red natural dyes. In this work, a set of dyed references were manufactured following Mexican recipes with red dyes (cochineal and brazilwood) in order to determine the characteristic FORS spectral features of fresh and aged dyed fibers for their identification in historical pieces. Based on these results, twenty-nine indigenous textiles belonging to the National Commission for the Development of Indigenous People of Mexico were studied. Cochineal and brazilwood were successfully identified by FORS in several pieces, as well as the mixture of cochineal and indigo for purple color.