Scientists in China have created what they claim are the first samples of reindeer hexagonal diamonda theorized rare variety of super-strong diamond found in meteorites from shattered dwarf planets.
Natural diamond, also called cubic diamond, has been considered that the hardest natural material on earth so long as the Mohs scale of hardness, which assesses minerals’ resistance to scratching, uses diamond as the scale’s upper limit. It is called cubic diamond for its neat arrangements of carbon atoms in a cubic structure. In contrast, hexagonal diamond organizes carbon atoms in a lattice made of hexagons, like a honeycomb.
An elusive mineral
In 1962, researchers at the Pittsburg Coal Research Center theorized that the layers of carbon atoms that make up diamond could be organized into a hexagonal lattice instead of a cubic lattice, thanks to how carbon forms bonds with other carbon atoms. In 1967, scientists discovered hexagonal diamond – or lonsdaleite – in the laboratory, and suspected that it might be harder than cubic diamond.
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They began looking for it in a special type of diamond-rich meteorite called ureilite, which forms from the mantle of shattered dwarf planets. The first detection of hexagonal diamond in the wild was documented in a 1967 paper; three Canyon Diablo meteorites (fragments of an asteroid that created a large crater in Arizona) with about 30% hexagonal and 70% cubic diamond phases, and Goalpara meteorites (found in Assam, India) which had a small amount of hexagonal diamond.
Not everyone agrees that Canyon Diablo lonsdaleite exists. Some researchers believed the evidence could be explained by defective cubic diamond which were stacked chaotically, and they were not convinced that lonsdaleite had been discovered in previous studies. However, several recent studies have identified lonsdaleite in meteorites and in laboratory samples, including a 2025 study that made small amounts of it in the laboratory.
The biggest challenge in identifying lonsdaleite is the lack of pure samples; in many cases it is mixed with cubic diamond, graphite and other minerals. This makes it difficult – or even impossible – to test and measure its unique properties.
The new study, published March 4 in the journal Naturesolved this problem by creating several pure hexagonal diamond samples approximately 0.06 inches (1.5 millimeters) in diameter—large enough to measure the samples’ material properties. The team found that hexagonal diamond is both stiffer and harder than cubic diamond, and that it resists oxidation much more than cubic diamond does. This means that hexagonal diamond can withstand much higher temperatures without the surface being destroyed by reacting with oxygen, which is important for applications such as drilling.
First proof of hexagonal diamond?
The study also provides great evidence that hexagonal diamond is a real material. According to the study, “structural and spectroscopic analyses, supported by large-scale molecular dynamic simulations, unequivocally confirm the identity of HD (hexagonal diamond).”
To make the samples, the researchers compressed highly organized graphite (graphite with carbon atoms neatly arranged) for 10 hours at 20 gigapascals, or about 200,000 times Earth’s atmospheric pressure at sea level, and exposed them to temperatures ranging from 2,300 to 3,400 degrees Fahrenheit. Celsius). At higher temperatures and pressures, the lonsdaleite began to transform into cubic diamond.
Hexagonal diamond can improve processes and tools that currently rely on cubic diamond, such as drilling and cutting tools, polishing abrasive coatings and dissipating heat from electronics. Its presence in meteorites can also tell us a lot about how the meteorite was formed and where it came from, providing more clues about our solar system.
The elusive material “has potential applications in many fields, such as in cutting tools, in thermal management materials and in quantum recording”, Chong-Xin Shanco-leader of the new Nature study and a physicist at Zhengzhou University, said Nature in an article.
The new study also provides “a practical strategy to produce HD (hexagonal diamond) in bulk form,” opening the way for larger samples, more scientific exploration and industrial applications that are no longer limited by cubic diamond’s hardness, according to the authors.
Lai, S., Yang, X., Shi, J., Liu, S., Guo, Y., Yan, L., Zang, J., Zhang, Z., Jia, Q., Sun, J., Cheng, S., & Shan, C. (2026). Bulk hexagonal diamond. Nature. https://doi.org/10.1038/s41586-026-10212-4
