Sourcing and pseudo-archaeology

By Mark Golitko, Associate editor for lithic studies and network analysis

One of the primary jobs of archaeological chemistry as it intersects with lithic studies is the identification of which source outcrops from which particular lithic materials originated. Williams-Thorpe once referred to obsidian sourcing as one of the “great success stories” archaeometry. Archaeometric studies of lithic materials have demonstrated the vast distances over which materials were moved in the past—to take one example from my own area of research, the SW Pacific, obsidian from the Kutau/Mt. Bao source on New Britain was transported over several thousand linear kilometers, being found in archaeological sites as far distant as Borneo and Tonga. Yet we remain less certain about how to interpret and model the intermediary steps through which a particular piece of raw material or finished object travelled to reach its final archaeological resting place. 


After a flurry of obsidian studies in recent years, particularly after the introduction of portable/hand-held XRF devices, 2020 appears to have been a bit of a slow year for new published sourcing studies (at least judging from the Web of Science Database, although the final verdict is not yet in). One notable recent paper by Matthew Boulanger ( rights and content), published in Journal of Archaeological Science: Reports, explores the perplexing issue of how a piece of Sierra de Pachuca obsidian (an economically important source in prehispanic times located north of modern Mexico City) found its way to the Haleakalā crater on Maui, some 6000 km distant. While there has been considerable recent debate about the possibility that Polynesians had short-lived contacts with people in South America, taking the sweet potato into the Pacific, and leaving the chicken, this would be an unprecedented find, as no contact with Mesoamerica (or Hawai’i for that matter) has been postulated or documented. More importantly, this piece of obsidian (a large projectile point) has been taken up by the pseudo/fantastical archaeology community as evidence of yet another vast archaeological conspiracy to hide the “true” past from the public (for some reason). His PXRF study conclusively shows that this piece did originate at the Sierra de Pachuca/Navajas source, but that technologically, it is not consistent with either Pacific or Mesoamerican production. The object is likely a piece recently made for the tourist industry, and was possibly transported to Maui as part of a New Age spiritual festival during the late 1980s, which among other places significant to participants, included gatherings both at the Haleakalā crater, and at Teotihuacan, a major prehispanic city located just north of Mexico City.


Reading this paper jogged my memory of a similar incident from earlier in my archaeometric career. While working as a post-doc at the Field Museum, I conducted chemical studies of many of the obsidian objects in the Field’s extensive collections. At one point, I requested access to all of the obsidian listed as originating from the area around New Guinea. When the collections were brought up to my lab, I immediately noticed that two objects didn’t seem to fit with the rest, being made on what were clearly prismatic blades (a technology absent in the New Guinea region) and having a distinctive greenish-gold color, much like the Maui Pachuca artifact. While I could already guess the source of these materials, like Boulanger, I decided to verify my hunch by collecting PXRF measurements on them. Not surprisingly, these objects are a perfect match for the Sierra Pachuca source. They do not chemically match any New Guinean sources, none of which are greenish in color, and only one of which (the East Fergusson Island source) has a peralkaline composition like the Pachuca source. Nor do they match the only other greenish peralkaline source for which I had data, the Bingöl A source in central Anatolia, a compositional type well represented in the Field’s collections from the early urban center of Kish (Figure 1). 

Figure 1. pXRF measurements on two pieces of greenish obsidian from the Field Museum's collections, compared to possible relevant raw material source samples.

Is this another example of hyper-diffusionism? Did prehistoric Polynesian voyagers move Pachuca obsidian across the entirety of the Pacific? Had I just blown-up a worldwide scientific conspiracy that I had unwittingly participated in for more than a decade? It seems unlikely—the Field purchased the objects in question from the major Hamburg-based museum dealer J.F.G. Umlauff early in the 20th century. Umlauff collected and sold objects from many areas of the world, including New Guinea and Mesoamerica, so undoubtedly, these Pachuca blades were miss assigned either by staff at Umlauff or the Field at some point. Perhaps some of our archaeo-mettalurgical colleagues could run some similar experiments on the mysterious “monoliths” that have appeared in recent weeks to see where they came from!