Portable X‐Ray Fluorescence Spectroscopy of Pictographs: A Case Study From the Lower Pecos Canyonlands, Texas

Abstract

We evaluate the effectiveness of non-destructive portable X-ray fluorescence spectroscopy (pXRF) for elemental analysis of pictographs at 10 sites in the Lower Pecos Canyonlands of Texas. Considerations and limitations of pXRF analysis are discussed to inform future research. We found that manganese and iron minerals were the main constituents of black and red paints, respectively. However, 40 pXRF measurements from 31 images tested at 41VV75 and 41VV76 did not contain manganese, suggesting charcoal pigment-the first widespread documentation of charcoal figures in the area. The identification of charcoal-based pigments is important for rock-art and radiocarbon studies in the region.

Non‐Destructive or Noninvasive? The Potential Effect of X‐Ray Fluorescence Spectrometers on Luminescence Age Estimates of Archaeological Samples

“…Similarly, a naturally spalled flake of sandstone rock shelter with applied and natural pigmentation from the Kimberley region of northwestern Australia (Figure ) was included in this experiment due to the potential of dating rock surfaces to establish an age for the associated rock art (Sohbati et al., ). pXRF is becoming routinely used in situ to analyze rock art pigments (Roldán et al., ; Olivares et al., ; Huntley et al., ; Koenig et al., ) and site taphonomy (Huntley, ; Ogburn, Sillar, & Sierra, ). Our experiment demonstrated that this type of in situ analysis can induce luminescence in the rock surface itself, especially on the “fresh” unexposed grains as discussed earlier.…”

Strategies for14C Dating the Oxtotitlán Cave Paintings, Guerrero, Mexico

“…To distinguish between inorganic, mineral-based pigments and PyC pigments, we analyzed the paintings in situ using a handheld portable X-ray fluorescence (HHpXRF) spectrometer. This technique has proven effective in the study of rock art primarily because it is noninvasive and provides qualitative/semi-quantitative data on chemical elements in the paints (Koenig et al 2014; Newman and Loendorf 2005; Roldán et al 2010; Rowe et al 2011). The method is especially useful for discriminating between mineral-based and carbon-based pigments, and thus for identifying specific paintings that could potentially be 14 C dated (Beck et al 2013; Koenig et al 2014; Rowe et al 2011).…”

“…This technique has proven effective in the study of rock art primarily because it is noninvasive and provides qualitative/semi-quantitative data on chemical elements in the paints (Koenig et al 2014; Newman and Loendorf 2005; Roldán et al 2010; Rowe et al 2011). The method is especially useful for discriminating between mineral-based and carbon-based pigments, and thus for identifying specific paintings that could potentially be 14 C dated (Beck et al 2013; Koenig et al 2014; Rowe et al 2011). While there has been controversy surrounding the use of HHpXRF for quantitative analyses of archaeological materials (Shackley 2010), our goal was simply to establish whether manganese or iron concentrations in paints were above the natural background levels of the bedrock.…”

“…Our sampling strategy at Oxtotitlán focused mainly on black paints because of the possibility that the pigments were prepared using pyrolyzed carbon (PyC), the byproduct of incomplete combustion of plants or animal fats and referred to as charcoal, soot, carbon black, or lampblack. Many black paints used to create parietal rock art in antiquity were constructed from manganese and iron oxide minerals (Chalmin et al 2003; Chalmin et al 2006; Hyman et al 1996; Koenig et al 2014; Littmann 1975; Magaloni, Newman, et al 1995; Vázquez et al 2008; Zoppi et al 2002); however, PyC was also commonly used, thus providing a source of carbon for direct radiocarbon analysis (Baker and Armitage 2013; Bonneau et al 2011; López-Montalvo et al 2014; Magaloni 2001; Morwood et al 2010; Valladas et al 1992; Valladas et al 2001).…”

Nondestructive Techniques in the Study of a Gilded Metallic Sword From the Islamic Art Museum

“…The energy of any given secondary XRay is characteristic of a specific element, allowing qualitative identification of elements present in a sample. In addition, the detector also counts the number of secondary X-Ray from the sample, allowing quantitative elemental concentrations to be determined [17][18][19].…”