X-ray tech penetrates rock to detect diamonds

German scientists have developed a new X-ray technique that can help locate diamonds hidden deep in rocks.
The Fraunhofer Institute's Development Center for X-ray Technology EZRT in Furth, Germany has developed a demonstrator that detects diamonds hiding inside rocks of volcanic origin.
The process is based on dual-energy X-rays. Two images of the same object are produced using two different X-ray spectra. An algorithm then filters out the data about the material from both images.
Different substances can be identified with very high reliability. The new technology is capable of detecting diamonds of just a few millimetres in size in kimberlite ore - of grain sizes up to 50 millimetres.

With the EZRT demo model, the crushed rocks pass through an X-ray machine at a speed of three meters per second. Both X-ray images produced provide data about the chemical atomic number of the materials - the number of protons in the respective nucleus.
Diamond is pure carbon, a relatively light-weight element with the atomic number 6. Kimberlite typically holds a conglomerate of silicates and aluminates.

Depending on the excavation area and mine, the atomic numbers vary between 12 and 14. The new algorithm uses this data.
It links them with the data from both X-ray images, separates the diamonds from the kimberlite, and displays the results on two separate images.

This method is not limited to the detection of diamonds. It can also be used in the processing of industrial coal, researchers said.
"The X-ray's eagle eye could even find the highly coveted rare earths that are concealed in old cell phones, computers, and television sets to utilise them," researchers said.
Currently, the diamond industry is already using X-rays in order to find the coveted gems. The conventional process, however, can detect the diamonds only at the surface of the ore.
The diamonds irradiated and activated by X-rays emit light in the optical spectrum.