International Obsidian Conference 2019 (original) (raw)
Related papers
Global perspectives on obsidian studies in archaeology
Quaternary International, 2020
For more than a half-century, obsidian provenancing has underpinned many archaeological investigations of peoples of the past. The pace of obsidian studies in this regard has gathered significantly since around 2007, and we review the literature to gain a sense of where this momentum has come from, and what it heralds. In part, there is a data revolution underway, arising thanks to the capabilities for rapid survey and analysis enabled by field-portable analytical equipment. Obsidian studies are also gaining a stronger foothold in regions of the world where the approach was previously under-exploited. Our survey spans progress made in obsidian studies in the Mediterranean, Central Europe, the Near East, the Caucasus, Northeast Asia and Tibet, the Eurasian Arctic and Alaska, Southeast Asia, the Americas, Oceania, and Africa and Arabia. We also consider methodological issues related to compatibility of differing geochemical analytical techniques, and the state of the art in obsidian geochemical classification. The proliferation of new observations brings opportunities in terms of development of regional and global databases, as well as challenges of calibration and validation of analyses made by different scientists and laboratories employing diverse instrumentation. Obsidian provenancing demonstrates the astonishing ranges of our ancestors' interactions and networks, sometimes exceeding 1000 km and involving maritime transport.
Latin American Antiquity, 2007
This paper presents the results of obsidian characterization analyses for Middle and Late Postclassic sites in the Yautepec Valley of Morelos, central Mexico. A large sample (N = 390) of obsidian blades from excavated domestic contexts at the site ofYautepix and from surface collected contemporary sites were assigned to a quarry source using X-ray fluorescence (XRF), and a subsample was also analyzed with instrumental neutron activation analysis (INAA). The use ofXRF allowed the authors to expand the number of artifacts initially analyzed by INAA. These larger samples of sourced material prove essential to answering research questions regarding regional economies, particularly with regard to issues such as production and exchange. This study demonstrates the complementarity of XRF and INAA and the specific advantages inherent in each of these techniques.
Keywords: Sierra de las Navajas (Mexico) Lipari (Aeolian Islands) Obsidian source analyses Obsidian color Microtexture Microvesiculation XRF and ICP-MS analyses a b s t r a c t Sierra de Las Navajas (State of Hidalgo, Mexico) and Lipari (Aeolian Islands, Italy) were among the most important sources for obsidian trade in Mesoamerica and in the Mediterranean during the Stone Age. In this paper obsidians from these two localities were compared in terms of their aspect, chemical composition, microcrystallinity and microvesiculation. In Sierra de las Navajas, the typical deep green obsidian with a golden hue has been analyzed together with a less common dark grey, porphyritic variety. Lipari obsidian is commonly black, but a light grey variety also occurs. Obsidian of both varieties was analyzed for this paper. Microvesicularity was investigated through Scanning Electron Microscope (SEM) observation, microporosimetry and, for Sierra de las Navajas green obsidian, through a preliminary X-ray computed microtomographic study. Crystallinity and micro-or nano-crystallinity were investigated through X-Ray Powder Diffraction and EDS (Energy Dispersion System) microanalyses. Finally, the chemical composition in terms of major and trace elements, including rare earth elements, was determined using X-Ray Fluorescence (XRF) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The comparison of samples of different colors suggests that the characteristic green color of Sierra de las Navajas obsidians could be related to their relatively high iron content, and to the occurrence of many elongated and iso-oriented vesicles which may also be responsible for the obsidian's golden hue. Low iron and an absence of vesicles give Lipari obsidian its " normal " black color. The light grey obsidian from Lipari probably owes its color and imperfect conchoidal fracture to numerous bubbles of less than 1 mm in size and to nano-crystallinity. Sierra de las Navajas obsidians show a significant chemical variability in terms of trace elements, that can be explained by common evolutionary processes in the magma chamber. However, this variability is also internal to a single volcanic complex and this makes the trace element contents unsuitable to differentiating between the different sub-sources of the same area. On Lipari, our data do not allow us to distinguish between the two sub-sources of Vallone del Gabellotto and Canneto Dentro on the basis of major and trace elements. On the whole, our study suggests that caution should be used for both Lipari and Sierra de las Navajas when identifying obsidian sub-sources on the basis of trace element contents.