Scientists at Los Alamos National Laboratory (LANL) in the US have confirmed a 7.68 oz (217.78 g) piece of gold is in fact a singular crystal, increasing its value from around US$10,000 to an estimated $1.5 million. The specimen, the largest single crystal piece of gold in the world, was discovered in Venezuela decades ago, but it is only by using advanced probing instruments that experts can now verify its authenticity.
Gold found in the ground will generally have a polycrystalline structure, meaning it is made up of many crystallites, varying in shape and size. Gold of a mono-crystalline structure, where the material is unbroken, are rarer and of significantly higher value. The US-based owner provided geologist John Rakovon with four gold specimens, hoping to determine whether they were of a polycrystalline or mono-crystalline structure.
Using a single-crystal diffraction (SCD) tool and a high-pressure/preferred orientation (HIPPO) instrument at the Los Alamos National Laboratory, Rakovan was able to examine the minerals using a technique called neutron diffractometry. As opposed to other probes, such as x-rays or electrons, neutrons allow the scientists to peer deep inside the materials and evaluate their structure.
The team found three of the four samples to be single-crystal pieces of gold. It is now preparing a scientific report and is examining the results to gain further insights into how the rare pieces may have originally formed.
“The structure or atomic arrangement of gold crystals of this size has never been studied before, and we have a unique opportunity to do so,” says Rakovan.
The techniques used to study the gold specimens is detailed in the following video.
Source: Los Alamos National Laboratory
It's values as an artifact, even if it were somehow manufactured, would normally be much higher anyway.