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The bulk of our laboratory services are geared towards archaeometric analyses of artifacts made of obsidian and, to a lesser degree, fine-grained volcanic (FGV) materials (including basalt). Unless you choose our discounted Basic Report option, each project is returned with a brief written report and detailed data tables (suitable for use as a standalone appendix). Individual descriptions of obsidian sources identified through trace element studies are (or soon will be) provided through our companion website at www.sourcecatalog.com. All projects are returned with an CD containing (1) a speadsheet with all analytical results, (2) graphics files of any figures that appear in your report, and (3) copies of any Adobe Acrobat files that were produced as part of your project (including the overall final report). For a downloadable sample of our reports, click HERE. Standard shipping (UPS, Fedex, or Certified/Delivery Confirmation mail) of artifacts and results is included with all projects.
To submit samples for analysis, please use the Adobe Acrobat sample submission form provided by Northwest Research. All samples should be sent to the lab in Corvallis, Oregon. For additional details on sending samples to the lab for analysis, click on the SUPPORT tab at the top of this page and choose the HOW TO link.
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Northwest Research owns and operates Spectrace 5000 and QuanX EC energy-dispersive X-ray fluorescence (EDXRF) spectrometers that are used to determine the trace and minor element composition of archaeological and geological specimens. Using a custom database management system, the results of the trace element analyses are compared with our extensive geologic source reference collection, allowing us to identify the geologic sources of obsidian and basalt artifacts. The patterns of source use that are revealed by the provenance analysis of artifacts can then be used to explore prehistoric procurement and exchange systems and may be used to indirectly examine a number of other prehistoric cultural processes.
The process of XRF trace element analysis is entirely nondestructive but is limited to obsidian and basalt artifacts with a minimum diameter of no less than about 10 mm and a thickness of no less than 1.5 mm. Larger specimens are preferred for analysis and should be selected whenever possible. Slightly smaller samples (5-10 mm) can also be analyzed under some cicumstances although the source assignment success rate for small items is often lower than for larger artifacts.
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When a surface of freshly-flaked obsidian is exposed to the air, water is slowly absorbed into the surface of the artifact, leaving a narrow hydration rim that is visible under a microscope. The thickness of the rim depends, in part, on the age of an artifact, and provides researchers with the opportunity to directly determine the approximate age of its manufacture.
point above as part of the process of measuring the hydration rim on the artifact. As is visible in the image above, the process of slide preparation is slightly destructive. A thin slice of glass is first carefully removed from the edge of an artifact. This thin wafer is fastened to a slide, ground to a thickness of about 30-50 microns, and is examined with a petrographic microscope. The hydration rim that has formed on the surface of the artifact can then be accurately measured to a precision of approximately +/- 0.2 microns.
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with the Silver Lake/Sycan Marsh source in Oregon. Any of the new services described above can requested by adding them to the "Other" section of our standard Sample Submission form. Be sure to specify which service you are interested in on the submission form or in a cover letter.
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