Characterization of the Monte Arci (Sardinia) Obsidian Sources

New Approaches to the Characterization of Obsidian from the Mediterranean Island Sources: Interpreting Chronological Change in Neolithic Sardinia and Corsica

“…The same set of 60 samples was also analyzed for 15 elements by XRF using a Spectrace 5000 spectrometer at the Northwest Research Obsidian Studies Laboratory. While these analyses demonstrated that as many as nine Sardinian sources may be identified, only four (SA, SB1, SB2, and SC) are of archaeological significance, since the Ceca sources are only represented by obsidian of unworkable size, the two SC source groups co-occur in the same area and are visually and physically indistinguishable, and the three SB1 source subgroups are only rarely represented among artifacts [6,16]. INAA, XRF and laser-ablation ICP-MS analyses are now underway to fully characterize the multiple source localities on the other central Mediterranean source islands, and preliminary results indicate the existence of four to six chemical source groups on Pantelleria, and two on Palmarola.…”

“…Early analyses of artifacts made of Sardinian obsidian suggested that multiple, chemically differentiable sources or flows exist on at least that island [3], and field and laboratory research by several teams has now resulted in the location and characterization of as many as nine chemically distinct obsidian source localities in the Monte Arci region, of which at least five were exploited in antiquity [6,[13][14][15][16][17]. Five chemical source groups have also been identified for Pantelleria [18]; obsidian occurs in two separate localities on Palmarola [19]; and multiple outcrops exist on Lipari as well [20].…”

“…For the full chemical characterization of geological samples, a combination of inductively coupled plasma mass spectrometry (ICP-MS) [34][35], neutron activation analysis, and X-ray fluorescence spectroscopy is employed. One hundred and seventy-four geological specimens from 20 collection localities in Sardinia were analyzed semi-quantitatively for 38 major and trace elements using a Fisons PQ 2 Plus quadrupole ICP mass spectrometer, and 125 samples were analyzed for 11 major and minor elements using a Cameca MBX electron microprobe equipped with wavelength dispersive spectrometers [16]. A subset of 60 samples was then quantitatively analyzed for 27 elements by INAA at the Missouri University Research Reactor.…”

“…The SEM with energy dispersive spectrometers also has been used for obsidian studies in the Mediterranean and elsewhere [37][38], but Ti, Mg, Mn and P are often below the minimum detection limits of EDS systems and these elements are often necessary for discriminating among the Mediterranean island sources and subsources. For the microprobe analyses, at least two points per sample were excited by a wide (40 ) 15 keV electron beam so as to avoid inadvertently heterogeneous points, and the X-radiation was measured by WDS with counting times of 10-80 s per element [16]. Results were standardized to a total of 99% allowing 1% for trace elements and structural water.…”

Long-Distance Obsidian Trade in Indonesia

“…The electron microprobe, equipped with wavelength dispersive X-ray spectrometers, was chosen for the analysis since this technique provides rapid, inexpensive and quantitative concentration data for all major and minor elements. A detailed description of the application of this technique to obsidian analysis has been published elsewhere and need not be repeated in its entirety here [26].…”