PIXE and ionoluminescence for Mesoamerican jadeite characterization

摘要

Greenstones were highly appreciated in pre-Hispanic Mesoamerica. Most of the finest green artifacts were worked in jadeite and other minerals such as serpentine and nephrite. Jadeite, the most precious stone in ancient Mesoamerica, was widely used and traded since the Preclassic Horizon (1500 B.C.). The main beds are located in the Maya region, in the Motagua area of Guatemala. In this work, three pieces of a necklace of greenstones from an offering (corresponding around 155 A.D.) discovered in an extensive excavation carried out in the palatial structure of Xalla, at Teotihuacan site, in the central highlands of Mexico, were studied using external beam particle induced x-ray emission (PIXE). The necklace is composed by 11 round pieces of green colors ranging from light to dark green. The aim of this study is to determine the elemental composition of the greenstones and to establish the sourcing, trade and relationship between these regions. Thus, several jadeite samples from Manzanal sources of Motagua were analyzed as well. The elemental composition comparison between the archaeological items and the known jadeite samples indicates that only one archaeological piece is related to the Manzanal sample source. Green luminescence of high intensity was observed for the archaeological pieces but only in one case the luminescence was blue-violet. When comparing with green stone mineral samples, only jadeite presented luminescence. The spectra, corresponding mainly to Mn2+, Ce3+ and Al3+ emissions, were collected under proton induced luminescence in vacuum on the jadeite samples. No correlation was observed among light emission color and jadeite sources. Copyright (C) 2008 John Wiley & Sons, Ltd.