gems, jade, jadeite, fei cui, Mesoamerica, Mexico, Guatemala, Costa Rica, Mayans, Olmecs, Aztecs, geology

Jade is a semiprecious stone whose exploitation and commercialization in Guatemala dates back to the time of the Maya. Maya culture used jade not only as an ornament for nobles and priests, but also attributed healing powers to it, establishing a market for this stone throughout the empire. Beginning in 1952, when jade deposits in Guatemala were rediscovered, the exploration, extraction, and commercialization of jade jewelry and artifacts experienced renewed growth. Today, different varieties of jade are marketed, their value depending primarily on coloration. The present study employed X-ray fluorescence to determine variations in the content of chromophore elements within the chemical structure of jade, since these are responsible for the coloration of the mineral. The jade samples analyzed in this study were provided by companies that market jade primarily in Antigua Guatemala. Jade is characterized by colors ranging from white to green, sometimes even appearing black, with newer varieties displaying blue, champagne, and violet hues. Prior to chemical analysis, the samples were classified according to color, with the assistance of artisans from the workshops where the mineral is worked, and designated J-01 through J-17. After classification, the samples were ground and analyzed by X-ray fluorescence in the Geochemistry Laboratory of the Institute of Geology at the National Autonomous University of Mexico. During analysis, the concentrations of major and trace elements were determined. The results were interpreted in terms of the solid solutions formed during jade crystallization. The analytical results showed that samples with lighter coloration (J-01 to J-06) are classified as jadeites (NaAlSi₂O₆), whereas the darker samples (J-07 to J-16) belong to the ferroaugite phase (FeCaSi₂O₆). The chromophore elements identified include chromium, vanadium, nickel, zinc, cobalt, and copper. Jade coloration depends on the proportion of the Fe²⁺ ion and its relationship with each chromophore ion. Chemical analysis of jade may be used as a tool for identifying pre-Columbian artifacts of Guatemalan origin, since the formation conditions of this mineral are restricted to only a few regions around the world.