History & Activities

The application of neutron activation analysis (NAA) to investigate archaeological problems began in the mid-1950s, when scientists at Brookhaven National Laboratory (Sayre and Dodson 1957) recognized its potential for relating artifacts to source materials through their chemical signatures. The advantages of NAA over other analytical techniques were quickly recognized, including: (1) ease of sample preparation; (2) high precision; (3) simultaneous measurement of multiple elements; (4) outstanding replicability; and (5) excellent inter-laboratory comparability. Interest in NAA expanded throughout the 1960s, 1970s, and 1980s as a result of an increased curiosity in archaeological questions by physical scientists (e.g., Perlman and Asaro 1969; Harbottle 1976, 1982) and direct involvement of archaeologists (e.g., Bieber et al. 1976; Bishop 1975) in the application of nuclear analytical procedures.

The Archaeometry Laboratory at MURR was formally established in 1988 following the award of a laboratory-support grant from the National Science Foundation (NSF). Prior to 1988, archaeological research at MURR was conducted on a part time basis by several individuals: James Vogt, David Ives, Jeremy Edward and Mike Glascock. Since 1990, the principal investigators of the Archaeometry Lab have included Mike Glascock, Hector Neff, Robert (Jeff) Speakman, and Jeff Ferguson. The initial and subsequent NSF grants have facilitated a significant reduction in analytical costs for academic researchers from universities and institutes in the USA otherwise lacking access to affordable NAA. The Archaeometry Lab became popular almost immediately, and a continually increasing stream of archaeological specimens for NAA has arrived at MURR ever since. In addition to the NSF grant, the Archaeometry Lab is supported by cost recovery charges for the supplies consumed on NSF-subsidized projects and by occasional contracts with other federal agencies (e.g., National Park Service and Bureau of Land Management) and a number of cultural resource management (CRM) firms.

CRM firms and government agencies are beginning to recognize that NAA characterizations of cultural materials can enhance the quality and thoroughness of archaeological analysis, enhance the quality of contract reports, and can support the evaluation of sites for further investigation.  A poster symposium at the 2001 Society for American Archaeology Annual Meeting entitled Cultural Resource Management and Archaeometry: Entering the Mainstream provided concrete examples of this topic.  Archaeological reports presenting NAA results can help to maximize the information yield for projects of almost any size—large or small. For example, in southeast Missouri, where the National Park Service has funded hundreds of analyses to create a ceramics compositional database, NAA comparisons are successfully identifying sources of single sherds.  Our ceramics database in the American Southwest and California regions is substantial (>7,200 sherds & clays) and our obsidian sources database in the western USA is also substantial (>160 sources characterized) such that interesting comparisons of new data with old are highly possible.

Evidence for the popularity of the Archaeometry Lab at MURR includes its support for hundreds of research projects and analysis of more than 90,000 archaeological specimens since 1988. In addition, the Archaeometry Lab has provided research training for more than 30 students from the University of Missouri and more than 100 graduate students from other universities on dissertation and thesis projects, organized several workshops and symposia, and published more than 400 scholarly articles in journals and book chapters. Currently, the Archaeometry Lab receives about 5,000 archaeological specimens per year for analysis by NAA, ICP-MS and XRF.

Facilities and Instrumentation

MURR is a multi-disciplinary research and education center operated by the University of Missouri (MU) and is located in Columbia, Missouri. The Research Reactor provides MU with opportunities for research and graduate education in neutron-related sciences and engineering that are unmatched by any other university. The central focus of this research is the 10 MW light-water-moderated reactor that is the highest-powered university research reactor in the US. The reactor has a 150+ hour per week operating schedule or more than 90% of the available time. (This is the best operating schedule for any research reactor in the world).

In 2000, a VG Elemental Axiom SC magnetic sector high-resolution Inductively Coupled Plasma-Mass Spectrometer (ICP-MS) with 213 nm UV Microprobe II Laser Ablation system was installed in the Archaeometry Lab.  In general, sample preparation is more laborious for microwave digestion ICP-MS than for INAA; but the new method of laser ablation ICP-MS is much easier than either INAA or MD-ICP-MS.  Most important for LA-ICP-MS however is the ability to analyze new types of samples nearly non-destructively and to measure several elements not possible by INAA (e.g., Y, Nb, Mo, In, Bi, and Pb). In February 2001, a modern state-of-the-art X-ray Fluorescence (XRF) spectrometer with polarized light source was also installed at MURR.  An NSF grant in 2004, allowed the Archaeometry Lab to purchase a portable XRF spectrometer which we are testing in the lab for future use at museums and archaeological sites.  The addition of these complimentary techniques has enhanced the unique capabilities of the Archaeometry Lab to support a broad range of archaeological research including samples both large and small.

The Archaeometry Lab has two laboratory rooms for sample preparation. Equipment in the laboratories includes a fume hood, muffle furnace, drying oven, analytical balances, laboratory press, glove box, rock saws, petrographic microscopes, and one binocular microscope. Other general purpose laboratories with additional analytical balances and other specialized equipment are available when projects overflow the Archaeometry Lab room. In other rooms, the Archaeometry Lab operates three high-purity germanium (HPGe) detectors coupled to automatic sample changers and shares the use of two other detectors with another MURR research group. A network of MicroVAX and IBM-compatible computers for data processing and report generation exists. The Archaeometry Lab maintains an archival collection of reference samples from most archaeological samples previously analyzed by the laboratory.

The Archaeometry Lab also has ties with Mr. Louis Ross (Sr. Electron Microscope Specialist at MU) who operates a scanning electron microscope (SEM) for use on some archaeological materials also undergoing bulk characterization by NAA. Characteristics of elemental distributions in ceramic pastes such as uniformity, association with particular kinds of mineral grains, or correlation with other measured elements may permit sources of compositional patterning observed in the bulk data to be ruled out. The ultimate goal is to enhance the precision of inferences derived from ceramic compositional analysis.

Archaeometry Laboratory Staff

The MURR Archaeometry Laboratory is operated by a team of highly skilled scientists, technicians and students.

Group Leader

Dr. Michael D. Glascock (Ph.D., 1975, Iowa State University) is a Sr. Research Scientist and Group Leader of the Archaeometry Lab. He has over 25 years of experience with NAA and gamma-ray spectroscopy as applied to archaeology, geochemistry, and environmental science. His current research focus involves obsidian source and artifact characterization in the Western Hemisphere.

• Where in the World is Michael Glascock? A photographic log of Mike's travels around the globe.

Technical Personnel

Mr. Jeffrey R. Ferguson (Ph.D., 2007, University of Colorado) is a Senior Research Specialist with an interest in lithic materials from the western US.

Mr. Matthew T. Boulanger (graduate student, Department of Anthropology, MU) is a Senior Research Laboratory Technician (and Archaeometry Laboratory Web master) interested in the archaeology of Eastern North America, the development of complex societies, computer applications in archaeology, and lithic sourcing. [visit Matt's personal website]

Ms. Corinne N. Rosania (graduate student, Department of Anthropology, MU) is a Research Laboratory Technician interested in paleoanthropology, zooarchaeology, and conservation biology. 

Students

Three MU graduate students, Mark O. Beary (Ph.D. candidate in Anthropology), Magen Coleman (Ph.D. candidate in Chemistry), and Mark Hammond (Ph.D. candidate in Art History & Archaeology), and four MU undergraduates Andrea Gioia, Chris Bodine, Tuesday Critz, and Jacob Masters also participate in research on archaeological obsidian, ceramics, chert, metals, and bone.

Interns

One internship position for three-to-four-month visits is supported on a year-round basis for visiting Ph.D. candidates from other U.S. academic institutions.

Non-MURR collaborators

Mr. Robert (Jeff) Speakman (Ph.D candidate at MU), former Senior Research Specialist at the MURR Archaeometry Laboratory, is currently the Director of Technical Studies at the Smithsonian Institution in Washington, DC.  Jeff maintains interests in Mimbres ceramics from the American Southwest and in obsidian from Beringia.

Dr. Hector Neff (Ph.D., 1984, U of California–Santa Barbara), former Senior Research Scientist at the MURR Archaeometry Laboratory from 1990 to 2002, is a Professor of Anthropology at California State University–Long Beach, and he collaborates with the Archaeometry Lab by maintaining the ceramic databases.  He is interested in investigating ancient production and exchange of artifacts, including obsidian, pottery, and chert/flint. His specific research areas include both Pacific coastal and highland Guatemala.

Three other collaborators of note are Dr. Frances M. Hayashida (Ph.D., 1995, U of Michigan), who is a Professor of Anthropology at the U of Missouri interested in Peruvian archaeology, Dr. Christophe H. Descantes (Ph.D., 1998, U of Oregon), who is interested in Pacific and Caribbean island archaeology, and Dr. Leslie G. Cecil (Ph.D., 2001, Southern Illinois University) who is an Assistant Professor in anthropology at Stephen F. Austin State University interested in Post-Classic Maya pottery studies.

Other students and faculty from MU's Department of Anthropology, Department of Art History and Archaeology, Department of Geological Sciences, and Department of Chemistry are frequently involved in research projects being conducted in the Archaeometry Lab at MURR. 

Dr. Glascock and his staff maintain frequent contact with collaborators of the Laboratory, approve final project design, supervise students, perform data analysis and interpretation, generate final reports, and collaborate in writing publications. The technicians oversee day-to-day operation of the laboratory, order supplies, schedule and irradiate samples, train students, write laboratory procedures, and produce graphics. Student employees prepare samples, perform sample irradiations, collect data, and assist in various aspects of data analysis and interpretation. In addition, the students are strongly encouraged to pursue research projects of their own design.

Archaeological Research at MURR

Since its inception, the Archaeometry Lab has collaborated on hundreds of research projects from around the world. Among the foremost of these has been the characterization and compilation of obsidian sources in Mesoamerica. After more than a decade of research, the resultant obsidian database contains chemical "fingerprints" for 25–27 elements each for all of the major and most minor obsidian sources in Guatemala, Honduras, and central Mexico. The database represents the most comprehensive collection of information on Mesoamerican obsidian sources known (Glascock et al. 1998). As MURR assembles its database of chemical fingerprints, a portion of each obsidian source is being stored for future reference, experiments in hydration dating, and exchange with other analysts and archaeologists. Sourcing of obsidian artifacts is now so routine that of more than 16,000 artifacts from archaeological sites around the world characterized to date, greater than 99% have been successfully assigned to one of the sources in our database. Collaborations with a number of archaeologists in Mesoamerica and elsewhere in the Western Hemisphere continue to expand MURR's obsidian database such that almost 400 sources from northern Alaska to the southern tip of Chile have been studied. In addition to these New World source characterizations, we continue to expand our database of Old World obsidian sources in regions such as the Russian Far East, Japan, and the Mediterranean. In certain regions (Glascock et al., 1994), abbreviated-NAA methods that measure a limited suite of elements have been successfully developed to source obsidian artifacts more economically.

Although the Archaeometry Lab initially focused its attention on obsidian characterization, interest in pottery analysis has since grown rapidly such that more than 60% of the samples we analyze each year are pottery, clays, and other raw materials used in the production of ceramics. Whereas obsidian occurs in compositionally and spatially discrete sources, sources of ceramic raw materials are widespread primary or sedimentary soils, between which there are only fuzzy spatial and compositional boundaries. Potters further confound the analysis of pottery by intentional addition or subtraction during paste preparation. Routine analysis of pottery at MURR generates a fingerprint for up to 33 elements in most instances. Approaches being applied on MURR-associated projects include intensive raw material sampling, studies of firing temperature and shell-tempering effects, thin-section petrography, and SEM imaging of the ceramic microstructure. Regions with large numbers of pottery samples analyzed at MURR include the Pacific coast of Guatemala, the Valley of Mexico, the American Southwest, the Mississippi Valley, and the eastern Mediterranean. Currently, our ceramics and clays database and ceramics archival collections contain nearly 42,000 samples.

Cryptocrystalline silicates include lithic materials such as chert or flint and were widely used by prehistoric peoples to manufacture stone tools. In contrast to obsidian and pottery, cryptocrystalline silicates (chert hereafter) have proven far more difficult to source by most analytical techniques, including NAA. In cases where chert is obtained from a single geological formation that outcrops at widespread locations, the within-source variation for many elements, if not most, is as great as the between-source variation. This problem suggests that analytical methods that determine the largest possible number of trace elements offer the greatest potential for success in identifying source-specific compositional profiles. The success achieved at MURR in the source analysis of chert is due in part to the large number of elements determined (approximately 30) and the excellent precision obtained for most elements. Thus far, more than 4,000 chert samples have been analyzed at MURR from sources throughout the Great Plains, Midwest, Alaska, Belize, and France.

Other archaeological materials such as basalt, copper, glass beads, steatite, limestone, marble, tephra, turquoise, shell, bones, and teeth are analyzed by the Archaeometry Lab on an infrequent basis.

Data Exchanges & Inter-Laboratory Collaborations

The Archaeometry Lab maintains a continuous information exchange with scientists from the earlier-established NAA programs at Brookhaven National Laboratory, Lawrence Berkeley National Laboratory, and the British Museum. The main reason for maintaining ties is the desire to promote inter-comparability of pottery and obsidian data through the use of common standards. More importantly, successful exchanges of data have been conducted as a means of maximizing the return on the investments in NAA conducted for archaeology over the past 40 years. To promote inter-laboratory use of our data, we store in the dBASE format used by the Smithsonian Institution, which easily converts to other formats. Large portions of our database have already been transferred to the Smithsonian Institution and vice versa. When merged with data from the other laboratories, the overall compositional data bank of approximately 125,000 analyses becomes an outstanding tool for archaeological research. An example of combining data from different laboratories was reported in a study of Mixteca-Puebla polychrome pottery (Neff et al. 1994). One foresees the possibility that a single sample can some day be reasonably compared to thousands of samples from hundreds of previously analyzed sources with the prospect of determining probabilities of match. We are presently working on inter-calibrations with labs that use techniques other than NAA (e.g., ICP-MS at California State University – Long Beach; XRF with Northwest Obsidian Research Laboratory) with the goal of enhancing our ability to exchange data. 

Education & Research Training

One of the Archaeometry Lab's most important activities involves the education and training of students from the University of Missouri and other universities. Because our students participate in the entire analysis beginning with sample preparation, irradiation, and measurement and continuing through the statistical analysis and data interpretation, they are well prepared to conduct research in academic and industrial environments. Since 1992, our internship program has enabled 20 PhD students and 3 post-docs from other universities to visit the Archaeometry Lab for periods of 3–4 months for direct supervision and training in sample preparation, analysis, and data interpretation. Thus far, 56 Ph.D. (four from MU and 52 from other universities) and 23 M.A./M.S. (seven from MU and 16 from other universities) degrees have been completed with support from the Archaeometry Lab. Approximately 35 graduate students in the USA and other countries are currently working on PhD and M.A. degrees involving a research collaboration with the Archaeometry Lab.  Many of the students with whom we have worked have been recipients various awards, including three graduate students who received awards for “Outstanding Dissertation from the Society for American Archaeology”, one student who was awarded a prestigous NSF Graduate Research Fellowship, and several others have been awarded Fulbright Scholarships.  We believe that the research supported by our laboratory has enhanced the opportunities for these students to succeed as archaeologists and scientists.  Former students are now in faculty positions at various universities, including Penn State, Washington State, University of Nevada–Las Vegas, University of Colorado–Denver, University of California–Davis, University of California–San Diego, California State University–Sacramento, Northeastern Illinois University, University of Texas–Austin, Michigan Tech, Purdue University, University of Redlands, Vanderbilt University, Montclair State University, Beloit College, and Brock University in Canada.

Acknowledgements

The Archaeometry Lab gratefully acknowledges the support it has received from the National Science Foundation through laboratory-support grants and research equipment grants. Our colleagues at the University of Missouri and other universities and the staff an MURR continue to be strongly supportive. This support has helped to make the Archaeometry Lab a successful operation for the tremendous benefit of archaeological science. 

References

Bieber, A.M., Jr., D.W. Brooks, G. Harbottle, and E.V. Sayre (1976).
Application of multivariate techniques to analytical data on Aegean ceramics. Archaeometry 18: 59–74.

Bishop, R.L. (1975).
Western Lowland Maya Ceramic Trade: An Application of Nuclear Chemical and Geological Data Analysis. Ph.D. dissertation, Southern Illinois University (unpublished).

Glascock, M.D., G.E. Braswell, and R.H. Cobean (1998).
A systematic approach to obsidian source characterization.  In Archaeological Obsidian Studies: Method and Theory, edited by M.S. Shackley, pp. 15–65.  Plenum Press, New York.

Glascock, M.D., H. Neff, K.S. Stryker, and T.N. Johnson (1994).
Sourcing of archaeological obsidian by an abbreviated-NAA procedure. Journal of Radioanalytical and Nuclear Chemistry, Articles 180: 29–35.

Harbottle, G. (1976).
Activation analysis in archaeology. In Radiochemistry: A Specialist Periodical Report, vol. 3, edited by G.W.A. Newton, pp. 33–72. The Chemical Society: London.

Harbottle, G. (1982).
Provenance studies using neutron activation analysis: the role of standardization. In Archaeological Ceramics, edited by J.S. Olin and A.D. Franklin, pp. 67–77. Smithsonian Institution Press: Washington, D.C.

Neff, H., R.L. Bishop, E.B. Sisson, M.D. Glascock, and P.R. Sisson (1994).
Neutron activation analysis of late Postclassic polychrome pottery from central Mexico. The Mixteca-Puebla: Discoveries and Research in Mesoamerican Art and Archaeology, edited by H.B. Nicholson and E. Quinones-Keber, pp. 117–141. Labrynthos: Culver City, CA.

Perlman, I. and F. Asaro (1969).
Pottery analysis by neutron activation. Archaeometry 11: 21–52.