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It's typically four to eight weeks, although it can potentially run longer when we're backed up with work, when we're having hardware problems, or during the summer field season (see below) when we're out collecting more samples. We recommend that you give us as much lead time as possible - we're constantly analyzing new source material and a relaxed turnaround schedule will ensure that we'll have time to analyze any newly sampled sources in your site region. Spectrometer hardware problems are very infrequent but can potentially delay project completion from several weeks to several months. If you have contract deadlines that must be met, let us know what they are as far in advance as possible and we'll be glad to work with you to meet them. We'll be happy to send you a draft copy of your results in advance of the final report. If you don't need a standard final report but will be happy with only the source assignments, data tables, and a data disk, we can almost always significantly cut your project turnaround time. While our final report makes a nice-looking appendix, everything in it beyond the individual project data is available through the lab website. In the case of multi-stage and/or multi-year projects, we'll be happy to provide a comprehensive and updated final report at the end of the project. Let us know.
Sure thing. We have a special rapid turnaround rate for those of you in a big hurry. For an extra 35%, we'll drop everything else, forsake our families and friends, and focus on your job. Within two weeks, you'll have a copy of the results faxed or emailed to you. The extra charge covers overtime and strained relationships with our families and other customers. For obvious reasons, a two week turnaround may not be practical for rather large jobs or for the other reasons mentioned in the previous discussion of expected turnaround time. If you're absolutely counting on the rapid turnaround to meet a project deadline, it's essential to contact us in advance.
Please note that our regular and rapid turnaround during the summer months from June 1 to September 1 may be a bit irregular. During this period, we're engaged in hardware maintenance, catchup, cleanup, staff recovery, and, most importantly, summer fieldwork. We maintain a very active summer field schedule and are often out of the office during this period. However, we will regularly be in the lab during these months and will be checking the voicemail while we're out so don't hesitate to call for information or for help with projects. For more details about our current summer projects, click here.
Unless you request only the discount Basic Report (data tables and data disk), we'll send you a short final report in a format suitable for use as a report appendix. Our final report includes a brief description of our obsidian characterization and hydration methods, a summary of the results of the analyses, the locations and descriptions of any sources that were identified, and a copy of all data in table format. Due to the increasing popularity and accessibility of the World Wide Web, we're now supplementing lab reports with increasing amounts of up-to-date information available through our Web sites at www.obsidianlab.com and www.sourcecatalog.com and through the International Association for Obsidian Studies Obsidian Source Catalog. For downloadable samples of our lab reports, click here.
Not at all. Each project report (regular or basic) is also produced as an Adobe Acrobat (PDF) document which will be emailed to you as soon as we've completed it. A report in this format may be read with the free Adobe Acrobat reader that can be downloaded from Adobe - click HERE to download the Acrobat software.
Again, no problem. Your data is always included on disk along with your final report - in Excel (.xls), Quattro (.qpw), and comma-delimited (.txt) file formats. If you have any special data file needs, let us know and we'll try to accommodate you.
Try any of the following locations for information about specific source and obsidian-related resources that are available through the Internet. These locations also all accessible through the Northwest Research Home Page.
The price rate is based on the number of samples submitted. Prices last went up on January 1, 2005, and are likely to stay at that point for the next couple of years. For the latest prices, check the always current website price list. You can also download an Adobe Acrobat version of the price sheet and sample submission form.
No - we won't charge you for samples that turn out to be too small for XRF analysis. We carefully examine each artifact prior to analysis and will reject any samples that are clearly too small. If we're not sure, we'll attempt to analyze them and will not charge you if we are not successful.
Yes - we will charge you for samples that turn out to be non-obsidian or, in the case of FGV's, that are non-volcanic. However, we keep an eye out for duds when loading samples and won't charge you for anything that we are able to catch before analysis. If we suspect that samples are non-volcanic but aren't certain, we'll attempt to analyze them and will not charge you if we are not successful.
We will send you an invoice along with your final report. We accept checks, cash, PayPal, and selected credit cards (Visa and Mastercard).
We generally ship artifacts using UPS or Fedex. Each shipment is assigned a tracking number that can be followed via the UPS or FedEx websites. Certified (or Registered) mail is also an easy option and may be more convenient in some areas (use a return receipt if you want to be notified that we received the shipment). We usually package any artifacts for shipment in ziploc bags in a protective box with plenty of bubble wrap and/or styrofoam peanuts, a technique that works well to protect your valuable artifacts. It's always a good idea to place a return address inside the box in case the label gets torn off during shipment. Top this off with a liberal application of nylon strapping tape and the safe shipment arrival of your samples is almost guaranteed.
Although we've never had any problem with lab security, we take the protection of your artifacts seriously while they're in the lab. When we're not on the premises, our 24-hour security system will be watching over things.
In general, our obsidian source coverage is restricted to the western United States and British Columbia, Canada (although there are a few exceptions), and the Western Mediterrean. Coverage for most regions of Oregon, California, Nevada, Washington, Idaho, Utah, Wyoming, New Mexico, and British Columbia is very good. Our source database for Arizona and Alaska is growing but is still patchy. We also occasionally work with volcanic glasses in other geographic areas including Mexico and the Western Mediterranean (good coverage here), the Far East, Russia, and several Pacific Islands. If you're curious to see what geographic areas have been included in our more recent (1995 and on) reports, click here. If you're not sure whether or not our source database is adequate for your artifacts, call or e-mail and we can provide more details and/or referrals to other labs. To see which specific sources that we use in correlating artifacts and sources, see our obsidian source reference database list. Our geochemical source research program is quite active and new sources are constantly being added to our database. Currently, our FGV (fine-grained volcanic) source database is most relatively complete for sources located in the Lake Tahoe region in the Sierras of eastern California. We sometimes use published geochemical data for obsidian sources in areas for which we do not yet have adequate analyzed source collections. Because of interlaboratory and intermethod differences that may exist, we only use data from XRF laboratories with which we are familiar, i.e., those that use X-ray fluorescence spectrometry methods with identical or very similar hardware and analytical procedures.
No worries ... you probably need a simple upgrade to the new free Acrobat Reader. You can download a copy at the Adobe Reader website.
The BioSystems Obsidian Lab was originally organized by Thomas Jackson and Robert Jackson (no, they're not related), two California archaeologists who had become interested in obsidian characterization and hydration studies in the 1970's. The obsidian lab really got rolling in 1992 with the purchase of a Spectrace 5000 energy-dispersive XRF spectrometer. In late 1994, Tom and Rob left BioSystems to form Pacific Legacy, Inc., a California company specializing in cultural resource management. At that point, Craig Skinner (who had been working primarily with Oregon obsidians since 1981) was hired to manage the XRF and obsidian hydration labs. To date, well over 55,000 obsidian and basalt artifacts (plus several thousand source samples) have been analyzed at the lab. For the post-BioSystems chapter in the story, see the next section.
The BioSystems Obsidian Studies Laboratory began as a division of BioSystems Analysis, a firm whose parent office was located in Santa Cruz, California. When Craig came on in late 1994 to look after the obsidian labs, the XRF Lab was located in Santa Cruz and the hydration lab was situated in Sacramento. In late 1995 and early 1996, the two labs were reunited in Corvallis, Oregon. Kathy Davis, the longtime XRF analyst in Santa Cruz, also initially moved north with the spectrometer - she now lives in Sacramento, California. Jennifer Thatcher, the current obsidian hydration analyst, started in Corvallis immediately after the move and was trained by Jay King, the previous BioSystems obsidian hydration analyst. Shortly thereafter, BioSystems Analysis fell into financial difficulties and bankruptcy court. We took over management of the labs, changed the name to Northwest Research, made an offer for the lab assets, and finally bought the whole works in late 1996. The staff and hardware remain the same - only the name has been changed. All the BioSystems obsidian-related records, obsidian and basalt source material, and archived obsidian hydration slides are safely stored here in Corvallis.
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With XRF spectrometry, the specimen is bombarded with X-rays or high-energy electrons from a conventional X-ray tube located in the spectrometer. This causes a disturbance of the electron orbitals of atoms and the sample then emits secondary or fluorescent X-rays of wavelengths that are then detected with our spectrometer. The resultant spectra lines or peaks (see the figure below) are characteristic of the elements present in the specimen. The height of the peaks is directly proportional to the amount of each element - these are converted to quantitative parts per million figures by comparing them with rock standards of known chemical composition.
No. Aside from the fact that we may have to scrub or scrape away surface residues, you'll never know the artifact has been analyzed. The best candidates for nondestructive XRF analysis are artifacts that are of adequate sample mass (see below) and that have a relatively flat and clean surface available for analysis. While it's possible the increase the accuracy and precision of the analysis by using finely powdered samples that have been pressed into pellets, a considerable body of research now exists that demonstrates that nondestructive analysis of obsidian and fine-grained basalt artifacts is a very viable characterization method.
No. Samples may be safely handled immediately after analysis.
We assign geologic sources to analyzed artifacts by correlating the artifact with sources contained in our source reference database. This database currently contains approximately 65,000 analyzed source samples and artifacts and is continually updated with additional sample trace element data. Alternative correlation methods that are sometimes also used in provenience studies also include statistical techniques (cluster and principal components analysis) and graphical methods (bivariate scatterplots or ternary diagrams, for example). The visual appearance of the artifact may also be occasionally used to verify or reject an artifact source, although we never rely on visual methods except in a minor way. For more information about our correlation methods, click here.
An unknown source assignment can be attributable to three likely causes: (1) The source is simply not contained in our source reference database, (2) The trace element composition of the analyzed sample fell well outside of the range of variability of our source reference samples, or (3) There was an analytical problem of some kind. To deal with the first two issues, we maintain a very active source research program and we generally analyze a minimum of 15 source samples (when available). When sources with considerable variability are encountered, we continue to analyze samples until we are satisfied that we understand the expected range of trace element values. Analytical problems may be instrumental (spectrometer malfunction) or may be related to a specific sample problem (uneven surface geometry, surface residue, presence of phenocrysts in glass, small sample size). When we suspect that there may be an analytical problem of some sort, we often reanalyze suspect samples to try and isolate the source of the problem. Each set of analyzed samples also includes a monitor standard so that we can immediately spot and pinpoint instrumental difficulties.
Sometimes we're just lucky and stumble across an unknown source during our routine summer field work. More often, we wait and watch for geographic patterns of groups of unknowns to develop. By examining relative frequencies of unknown sources at dispersed archaeological sites (or geologic sampling locations), geologic maps, and geomorphic clues (e.g., drainage patterns), we have been able to so far chase down all but the most persistent mystery sources.
Easy. Just email or call and we'll be happy to see if we've found the source since your project was completed. Let us know the site name, lab project number, and specimen number(s) and we'll review our source reference database to see if any new sources have shown up on our radar.
Yes. Extensive experimentation in our laboratory has demonstrated that the absolute minimum size requirements for accurate trace element determinations of most samples is at least 1 cm in (minimum) diameter and 1 mm in thickness. Slightly larger samples will yield more robust trace elemt values and we prefer to analyze specimens at least 1.5 cm in diameter and 2 mm in thickness whenever possible. In any case, we do not recommend the use of small samples in complex source areas or regions where the source universe is poorly understood.
They often can. What we're actually analyzing is the surface layer of the artifact - if there's dirt, patina, or some encrustation present, the analysis will reflect the trace element composition of that material as well as the artifact. Because of this, the surface of the items to be analyzed should be clean and preferably free from labels or residues. A simple wash with tap water and a toothbrush will usually suffice for the job. However, if artifacts already have painted sample numbers, the numbers may be left intact - even when paint is removed, some residue is left behind and it's better if the location of the number is obvious. Interference to the analysis by paint, when it occurs, is usually reflected in elevated levels of titanium, zinc, or lead. Particularly persistent residues may be removed with an X-acto knife.
Different classes of artifacts will tend to reflect different procurement behaviors and patterns. In general, formed tools such as projectile points will tend to come from a wider variety of sources (higher source diversity) than unformed, utilitarian artifacts or debitage (lower source diversity). If you're looking at local raw material use, select debitage. To look at quarry behavior, choose cores. If you're looking for evidence of longer-distance procurement or interaction, you'll probably want to pick formed tools. Similarly, the analysis of temporally diagnostic projectile points may add a valuable dimension of time to the analysis. ore samples = greater source diversity. In other words, larger numbers of analyzed artifacts tend to yield larger numbers of different individual sources. The number of different geochemical sources of obsidian or basalt that are identified at a given site are affected by numerous environmental and cultural variables, most notably the number of available sources, their relative distance to the site, and the number of artifact samples that are characterized. In areas of low source diversity (e.g., southern California), few sources were used and a modest number of samples will provide a good overall idea of the range and proportion of sources that were used. In areas of high source diversity (e.g., the Fort Rock Basin of Oregon), many sources of obsidian were utilized and it will take a proportionately larger number of samples to reconstruct an accurate scenario of overall procurement patterns.
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Yes, to some degree. We remove a small slice of obsidian (approximately 1-1.5 mm wide and several mm deep) from the edge of the artifact. See below.
above as part of the process of measuring the hydration rim on the artifact.
No. There are no minimum specimen size requirements for obsidian hydration measurements. However, specimens smaller than about 5 mm are difficult to prepare for analysis and are largely destroyed during slide preparation. The occasional recuts that are sometimes needed will not be possible in this case and a higher number of unsuccessful rim measurements may result.
Of course. If you have any special requests regarding the location of measurements on any artifact or would like measurements made at more than one location on the artifact, please attach a separate sheet with tracings or photocopies of the sample(s) and well-marked hydration measurement locations. Please do not use correction fluid to mark locations - it interferes with both hydration rim visibility and with the trace element analysis. If the surface geometry of the artifact prevents us from placing it at the designated spot, we will attempt to sample the same artifact surface at another location.
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