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NMSU physics professor researches rare, single-crystal gold pieces

Gold collectors, appraisers and investors could benefit from research conducted by New Mexico State University associate professor of physics Heinz Nakotte at the Los Alamos National Laboratories at the Lujan Neutron Scattering Center. And they would want to know if the piece in question really was "worth more than its weight in gold."



Heinz Nakotte, associate professor of physics at New Mexico State University's College of Arts and Sciences is part of a research duo studying single-crystal gold pieces and other crystals at Los Alamos National Laboratories. (Photo by Dixon Wolf at Los A

Nakotte, of the NMSU College of Arts and Sciences, and his research partner, John Rakovan, a geologist from Miami University in Oxford, Ohio, are studying rare, single-crystal pieces of gold by looking at the atomic structure or, in essence - how they are put together. This "cutting-edge" technology differs from other appraising methods used even prior to the Klondike Gold Rush in the late 1840s. Before X-rays and other research methods were invented, an appraiser would determine the value of gold by weighing it and multiplying its market value.

Through this study Nakotte and Rakovan determine whether gold samples take the form of a single crystal or if they are comprised of multiple crystals to determine its worth. Determining the origin could be the difference between a piece that's worth little to a piece that's worth hundreds of thousands of dollars, since single crystals are extremely rare, he said.

To scientists, a "crystal" is a material where the atoms are arranged in a periodic or scientific fashion meaning a crystal might not have defining characteristics such as a shiny coating or hard exterior surface. For example, in science both diamonds and graphite are defined as "crystals" differing only in the way the carbon atoms within them are arranged, Nakotte said.

"Some quartz and glass, even though they glitter, have no periodic arrangement and, therefore, are not crystals but they are amorphous," he said. Amorphous materials don't exhibit a definite atomic structure as seen in crystals.

The value depends on whether the atoms within the three-dimensional crystal structure are aligned in a grid formation or not. If the atoms are not aligned in the piece, the structure is a "poly-crystal" instead of a single "crystal." This can be determined through a technique called neutron scattering, which is the method the team chose rather than using X-ray techniques that simply look at the surface.

Nakotte explained two ways to determine the structure: through X-ray diffraction or through neutron diffraction, using a single-crystal diffractometer beam to examine the material within.

The single-crystal diffractometer used to determine the gold or crystal's origin is a machine housed in the Lujan Center. With a size similar to that of a computer printer, the 20 x 20 centimeter detectors are able to look inside materials using diffraction or scattering techniques without damaging them. This technique is similar to studying light through optics but at an atomic level. Therefore, the practice of neutron scattering can be used to determine the interior properties of solids and liquids, he said.

Neutron scattering can be time-consuming, but Nakotte admitted that he'll take as much time as it needs. "I spend as much time in the lab as possible and drive from Los Alamos to Las Cruces frequently to teach classes," he said. "Frequently," might be an understatement. In less than 10 years, Nakotte put 400,000 miles on his car.

Nakotte achieved his professorship through a joint-appointment with NMSU and Los Alamos Neutron Science Center after doing post-doctoral work from 1994 to 1997. Nakotte's work with single crystals has gained popularity with researchers, companies, collectors and museums worldwide, which send him single crystals of other minerals - not just gold - in order for him to determine the structural properties and value of the material.

The ways single crystals are formed involve a very specific set of chemical components and high temperature environments, he said. Gold is created beneath the earth's crust, and single-crystal gold pieces, about the size of a golf ball, are rare to find. One which Nakotte examined under the beam was valued at about $100,000. Others have been appraised at close to $1 million. This size of gold specimen does not happen frequently in nature, but a team found several large pieces in Venezuela in 2008, he said. Not to encourage a gold rush, he added that collecting gold in its raw form is very dangerous and could, in some cases, cost your life as was the case of one collector who found the Venezuelan gold crystal.

Nakotte and Rakovan's research was published in December in Rocks and Minerals magazine. They will each submit an article to separate scientific journals.