Newswise — WASHINGTON, D.C., November 12, 2014 -- Geologist Timothy Rose of the Smithsonian Institution’s Analytical Laboratories is accustomed to putting his lab’s high-tech nanoscale scanning electron microscope (nanoSEM) to work evaluating the mineral composition of rocks and meteorites. Lately, though, the nanoSEM has been enlisted for a different kind of task: determining the authenticity of ancient Mesoamerican artifacts.

In ongoing studies, Rose and his colleague Jane Walsh have now analyzed hundreds of artifacts, including carved stone figurines and masks and ceramic pieces from the ancient Olmec, Maya, Teotihuacan and Mezcala civilizations dating from 1500 B.C. to A.D. 600. “With our modern imaging and analytical tools we can look at objects at very high magnification, which can reveal new details about how, and sometimes when, objects were created,” he said.

Rose will discuss the technology at the AVS 61th International Symposium and Exhibition, to be held Nov. 9-14, at the Baltimore Convention Center in Baltimore, Md.

The nanoSEM used by Rose and his colleagues has the ability to function over a range of pressures. “Being able to work in the low-vacuum mode allows us to put samples into the microscope au naturel without coating them with an electrically conductive material such as carbon, which would be almost impossible to remove from a specimen,” he said.

In one study, Rose and colleagues used the nanoSEM to study stone masks from Teotihuacan, a pre-Columbian site located 30 miles northwest of Mexico City. The masks, about the size of a human face, were too big to be put into the device (and, more importantly, could not be removed from their respective museums or drilled or otherwise altered to obtain samples for analysis). However, silicone molds that were made of the objects to study tool marks with an optical microscope did remove tiny mineral grains from deep within cracks and drill holes. Chemical evaluation of these grains using the nanoSEM’s X-ray spectrographic analysis system showed that some were diatoms—common single-celled algae with cell walls made of silica. Diatomaceous earth is “a very fine powdery siliceous rock comprised entirely of diatoms that would make very nice polish for the stone of these specific masks,” Rose said. “We believe we found abrasive grains and polish that was used in the manufacturing process.”

In a separate study of artifacts confiscated by the federal government, the researchers found some pieces to be partially coated with a layer of what looked to be modern gypsum plaster. In other words, the pieces were fakes. However, Rose noted, a surprisingly small percentage of the objects evaluated to date have shown modern tools marks or other evidence of recent origins. One unique ceramic handled pot analyzed in detail, for example, had five chemically distinct layers that appeared to be original Olmec fresco paint—a level of craftsmanship that, he said, is unlikely to have been the work of modern artisans.

Presentation #CS-FrM3, “Faces from the Past: Microbeam Imaging and Analysis of Artifacts from Ancient Mesoamerica,” is at 9:00 a.m. Eastern Time on Friday, Nov. 14, 2014.

###

MORE ABOUT THE AVS 61st INTERNATIONAL SYMPOSIUM & EXHIBITIONThe symposium takes place from November 9-14 at the Baltimore Convention Center, which is located at One West Pratt Street in Baltimore, Maryland, 21201. The headquarters hotel is the Sheraton Inner Harbor at 300 South Charles Street in Baltimore, Maryland, 21201.

USEFUL LINKSMain symposium website: http://www.avs.org/Meetings-Exhibits/Information Technical Program: http://www.avssymposium.org/Media Center: https://www.avs.org/About/Press-Media-Center Baltimore Convention Center: http://www.bccenter.orgSheraton Inner Harbor: http://www.sheratoninnerharbor.com

PRESSROOMThe AVS Pressroom will be located in the Charles Street Lobby Staff Office of the Baltimore Convention Center. Pressroom hours are Monday-Thursday, 8:00 a.m. - 5:00 p.m. Your press badge will allow you to utilize the pressroom to write, interview, collect new product releases, review material, or just relax. The press badge will also admit you, free of charge, into the exhibit area, lectures, and technical sessions, as well as the Welcome Mixer at 5:30 p.m. ET on Monday in Ballroom III of the Baltimore Convention Center and the Awards Ceremony and Reception at 6:30 p.m. ET on Wednesday night in Ballroom I-II of the Baltimore Convention Center.

To request free press registration, please contact Jason Socrates Bardi at [email protected] and Della Miller at [email protected].

ABOUT AVSFounded in 1953, AVS is a not-for-profit professional society that promotes communication between academia, government laboratories, and industry for the purpose of sharing research and development findings over a broad range of technologically relevant topics. Its symposia and journals provide an important forum for the dissemination of information in many areas of science and technology, enabling a critical gateway for the rapid insertion of scientific breakthroughs into manufacturing realities. See: http://www.avs.org/About

###