About Precious Metals Imaging
What we do
Precious Metals Imaging uses Resonant Ultrasound Spectroscopy (RUS) to determine if precious metals have been tampered with the substition of inexpensive metals.
Recent activities have revealed that gold and silver samples have been substituted with inexpensive metals of similar density. Currently, the precious metals industry must use destructive methods to determine if the gold, or silver bars (or coins) have been replaced with materials of little value. These methods include drilling into the sample or melting it. When a metal has been tampered with it can still have almost identical densities and unchanged dimensions. However, the metals elastic (mechanical stiffness) properties will vary greatly.
Resonant Ultrasound Spectroscopy identifies changes in the metals elastic properties by scanning the metal, in less than a minute, without destruction. Moreover, unlike other common nondestructive testing methods (specifically ultrasonic testing and Eddy current testing) RUS requires no expertise as the computer based systems makes all decisions regarding the purity of the sample. This innovative technique replaces the destructive methods the industry currently uses to determine if a precious metal has been counterfeited.
In early 2012, the question arose about the relevance of RUS to detect tungsten in gold. After performing numerous experiments, including some at the Royal Canadian Mint (RCM) it became obvious that Resonant Ultrasound Spectroscopy was an efficient method of detecting tungsten inserts down to a few percent. In every case, RUS was able to find the substitutions. With permission from the US Secret Service, we acquired multiple counterfeit coins to further establish the principles exposed in these pages.
About the Founder
George W. Rhodes teaches Chemistry and practices physics. His expertise is in the area of nondestructive testing (NDT), especially resonant ultrasound spectroscopy (RUS), but also including acoustic emission and electromagnetics. George has a Ph.D. in Physical Chemistry from the University of Utah and a BS in Chemistry from Arizona State University.
George has over 50 technical publications and 20 patents, many of which are in the RUS field.
He leads the PMI effort to commercialize RUS to inspect gold/silver bars and coins.