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Fig. 1. Elements of interest for the analysis of archaeological ceramics and sediments typically analyzed by XRF.

Figure 1 Elements of interest for the analysis of archaeological ceramics and sediments typically analyzed by XRF.

Related Figures (16)

Fig. 2. Biplots of measured vs expected concentrations of phosphorus for 20 CRMs analyzed by WD-XRF (blue triangle), ED-XRF (green circle), and pXRF (red square). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
Fig. 2. Biplots of measured vs expected concentrations of phosphorus for 20 CRMs analyzed by WD-XRF (blue triangle), ED-XRF (green circle), and pXRF (red square). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
Fig. 3. pXRF spectrum illustrating the lack of response (recorded counts) for sodium and minimal response for P even under optimal analytical conditions.
Fig. 3. pXRF spectrum illustrating the lack of response (recorded counts) for sodium and minimal response for P even under optimal analytical conditions.
Concentrations of P and Ca for the two samples in Fig. 6. Notice how the Ca escape peak is measured as P counts.
Concentrations of P and Ca for the two samples in Fig. 6. Notice how the Ca escape peak is measured as P counts.
Fig. 4. pXRF spectrum illustrating the spectral overlay interference created by the escape peak of Ca onto the Ka line of P.
Fig. 4. pXRF spectrum illustrating the spectral overlay interference created by the escape peak of Ca onto the Ka line of P.
Fig. 5. pXRF spectrum illustrating overlapping K line radiation.
Fig. 5. pXRF spectrum illustrating overlapping K line radiation.
Fig. 6. Biplots of measured vs expected concentrations of V, Cr, Co and Ni for 20 CRMs analyzed by WD-XRF (blue triangle), ED-XRF (green circle), pXRF clay/sediment calibration (red square), and pXRF ‘mudrock’ calibration (black diamond). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
Fig. 6. Biplots of measured vs expected concentrations of V, Cr, Co and Ni for 20 CRMs analyzed by WD-XRF (blue triangle), ED-XRF (green circle), pXRF clay/sediment calibration (red square), and pXRF ‘mudrock’ calibration (black diamond). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
Fig. 7. Biplots of measured vs expected concentrations of Ba for 20 CRMs analyzed by WD-XRF (blue triangle), ED-XRF (green circle), pXRF clay/sediment calibration (red square), and pXRF ‘mudrock’ calibration (black diamond). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
Fig. 7. Biplots of measured vs expected concentrations of Ba for 20 CRMs analyzed by WD-XRF (blue triangle), ED-XRF (green circle), pXRF clay/sediment calibration (red square), and pXRF ‘mudrock’ calibration (black diamond). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
Fig. 8. Biplots of measured vs expected concentrations of the low-Z elements for 20 CRMs analyzed by WD-XRF (blue triangle), ED-XRF (green circle), pXRF clay/sediment cali- bration (red square), and pXRF ‘mudrock’ calibration (black diamond). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
Fig. 8. Biplots of measured vs expected concentrations of the low-Z elements for 20 CRMs analyzed by WD-XRF (blue triangle), ED-XRF (green circle), pXRF clay/sediment cali- bration (red square), and pXRF ‘mudrock’ calibration (black diamond). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
obsidian CRMs, and reliable analysis of ceramic and sediments re- quires a calibration built using clay and sediment CRMs. Archaeo- logical ceramics and sediments are often considered comparable to rocks: both are formed by geologic processes, composed of discrete mineral phases, and have similar geochemistry. However, sedi- ments and rocks differ in several significant ways which prevent rocks, even sedimentary rocks such as mudstones, from being a ‘matrix match’ for archaeological ceramics and sediments. cementing the sediments into rock. Sediments and clays, on the other hand, have not been through the lithification process and contain their original water content both as structural water and hydrous phases. Drying sediment samples prior to pressing them into pellets removes water absorbed by the sediments/clay min- erals but is typically at temperatures too low to drive off the structural water. Fired clay or ceramic has typically reached tem- peratures high enough for long enough to cause dehydration and dehydroxylation. However, during the subsequent cooling of the vessel, its use and/or deposition, ceramics absorb water into their void space and minerals rehydroxylate. Thus, archaeological ce- ramics and sediments have a higher structural water content than sedimentary rocks.
obsidian CRMs, and reliable analysis of ceramic and sediments re- quires a calibration built using clay and sediment CRMs. Archaeo- logical ceramics and sediments are often considered comparable to rocks: both are formed by geologic processes, composed of discrete mineral phases, and have similar geochemistry. However, sedi- ments and rocks differ in several significant ways which prevent rocks, even sedimentary rocks such as mudstones, from being a ‘matrix match’ for archaeological ceramics and sediments. cementing the sediments into rock. Sediments and clays, on the other hand, have not been through the lithification process and contain their original water content both as structural water and hydrous phases. Drying sediment samples prior to pressing them into pellets removes water absorbed by the sediments/clay min- erals but is typically at temperatures too low to drive off the structural water. Fired clay or ceramic has typically reached tem- peratures high enough for long enough to cause dehydration and dehydroxylation. However, during the subsequent cooling of the vessel, its use and/or deposition, ceramics absorb water into their void space and minerals rehydroxylate. Thus, archaeological ce- ramics and sediments have a higher structural water content than sedimentary rocks.
‘ig. 9. Biplots of measured vs expected concentrations of the mid-Z elements for 20 CRMs analyzed by WD-XRF (blue triangle), ED-XRF (green circle), pXRF clay/sediment cali- ration (red square), and pXRF ‘mudrock’ calibration (black diamond). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of his article.)
‘ig. 9. Biplots of measured vs expected concentrations of the mid-Z elements for 20 CRMs analyzed by WD-XRF (blue triangle), ED-XRF (green circle), pXRF clay/sediment cali- ration (red square), and pXRF ‘mudrock’ calibration (black diamond). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of his article.)
Clay and sediments CRMs used to build the clay/sediment pXRF calibration at CAIS.
Clay and sediments CRMs used to build the clay/sediment pXRF calibration at CAIS.
The 20 CRMs used to evaluate performance of clay/sedi- ment and ‘mudrock’ pXRF calibrations.
The 20 CRMs used to evaluate performance of clay/sedi- ment and ‘mudrock’ pXRF calibrations.
Expected and measured concentrations for SARM 69 using INAA, WD-XRF, ED-XRF, pXRF clay/sediment calibration and pXRF ‘mudrock’ calibration. Major elements are reported as wt%; minor and trace elements reported as ppm unless otherwise stated. Uncertified concentrations reported in brackets. Concentrations reported in shaded cells are informational only. Expected and measured concentrations for major ele- ments reported as elements were converted to oxides using the conversion factors in Glascock (2006). These values are marked with an asterisk (*).
Expected and measured concentrations for SARM 69 using INAA, WD-XRF, ED-XRF, pXRF clay/sediment calibration and pXRF ‘mudrock’ calibration. Major elements are reported as wt%; minor and trace elements reported as ppm unless otherwise stated. Uncertified concentrations reported in brackets. Concentrations reported in shaded cells are informational only. Expected and measured concentrations for major ele- ments reported as elements were converted to oxides using the conversion factors in Glascock (2006). These values are marked with an asterisk (*).
Analytical protocols used to evaluated performance of clay/sediment and ‘mudrock’ PXRF calibrations. Table 4 spectrum collected in air/no vacuum. This spectrum also illustrates that in air, with the exception of the two low-Z elements present in high concentration (Al and Si), no counts are recorded for elements below the Rh Compton peak, Z < 19. Under partial vacuum, the argon peak is no longer visible, however X-rays for elements Z < 13 are not recorded (Fig. 10). The spectrum collected with helium (He) flowing through the chamber/window, displacing all the air
Analytical protocols used to evaluated performance of clay/sediment and ‘mudrock’ PXRF calibrations. Table 4 spectrum collected in air/no vacuum. This spectrum also illustrates that in air, with the exception of the two low-Z elements present in high concentration (Al and Si), no counts are recorded for elements below the Rh Compton peak, Z < 19. Under partial vacuum, the argon peak is no longer visible, however X-rays for elements Z < 13 are not recorded (Fig. 10). The spectrum collected with helium (He) flowing through the chamber/window, displacing all the air
Fig. 10. pXRF spectrum comparing the detection of low-Z elements in air (green), under partial vacuum (blue) and with a helium flow (red). (For interpretation of the references t« color in this figure legend, the reader is referred to the web version of this article.) conducted specialized studies where sampling and/or export of samples was prohibitive. In contrast to earlier instruments which required specialized scientific knowledge, modern pXRF in- struments have become little more than point-and-shoot devices requiring little-to-no specialized knowledge. The desire to use these instruments as an inexpensive short cut to quantitative bulk chemical analysis of archaeological materials, such as ceramics and sediments, is understandable and has resulted in numerous studies that would not have been possible otherwise. However, as dis- cussed elsewhere (Speakman and Shackley, 2013), these analyses must be undertaken with caution and some degree of under- standing of the physics involved. Unlike obsidian, for which it is relatively easy to determine a geologic/geographic source, prove- nance studies of ceramics are inherently challenging under the best of circumstances, using some of the more powerful analytical techniques (Hunt, 2012). It is primarily for this reason that ar- chaeologists historically have not used XRF for provenance studies of ceramics; despite the large number of laboratory based ED- and WD-XRF spectrometers available at virtually every major institu- tion, in most cases, XRF is insufficient for provenance determina- tion of archaeological ceramics. top ED-XRF spectrometers for certain elements. However, a pXRF spectrometer cannot accurately quantify Na, P, V, Cr, Co, Niand the L lines of Ba in an archaeological ceramic or sediment matrix at the concentrations in which they are typically present. As a result of these limitations, compositional analysis of archaeological ceramics and sediments by pXRF cannot and should not be considered a substitute for fully quantitative analysis by WD-XRF, INAA and/or ICP-MS.
Fig. 10. pXRF spectrum comparing the detection of low-Z elements in air (green), under partial vacuum (blue) and with a helium flow (red). (For interpretation of the references t« color in this figure legend, the reader is referred to the web version of this article.) conducted specialized studies where sampling and/or export of samples was prohibitive. In contrast to earlier instruments which required specialized scientific knowledge, modern pXRF in- struments have become little more than point-and-shoot devices requiring little-to-no specialized knowledge. The desire to use these instruments as an inexpensive short cut to quantitative bulk chemical analysis of archaeological materials, such as ceramics and sediments, is understandable and has resulted in numerous studies that would not have been possible otherwise. However, as dis- cussed elsewhere (Speakman and Shackley, 2013), these analyses must be undertaken with caution and some degree of under- standing of the physics involved. Unlike obsidian, for which it is relatively easy to determine a geologic/geographic source, prove- nance studies of ceramics are inherently challenging under the best of circumstances, using some of the more powerful analytical techniques (Hunt, 2012). It is primarily for this reason that ar- chaeologists historically have not used XRF for provenance studies of ceramics; despite the large number of laboratory based ED- and WD-XRF spectrometers available at virtually every major institu- tion, in most cases, XRF is insufficient for provenance determina- tion of archaeological ceramics. top ED-XRF spectrometers for certain elements. However, a pXRF spectrometer cannot accurately quantify Na, P, V, Cr, Co, Niand the L lines of Ba in an archaeological ceramic or sediment matrix at the concentrations in which they are typically present. As a result of these limitations, compositional analysis of archaeological ceramics and sediments by pXRF cannot and should not be considered a substitute for fully quantitative analysis by WD-XRF, INAA and/or ICP-MS.
Related topics:
Archaeological Method & TheoryCeramicsScientific Analysis of Archaeological CeramicsAnthropogenic SedimentsPortable X-ray Fluorescence
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