How Quartz Transforms Under Extreme Pressure – Insights from Advanced Computer Simulations

What happens to quartz at the surface of the Earth when it’s hit by an asteroid? Our new study provides detailed insights into the time-resolved structural alterations through cutting-edge machine learning computer simulations. We discovered that depending on how pressure is applied—fast/slow and from multiple directions—quartz can take on entirely different structures. These findings can help explain typical shock features seen in ancient impact craters and open new doors for studying materials at extreme conditions. It’s a striking example of how AI helps to unlock secrets hidden deep in the structure of our planet’s most familiar minerals.

Figure 1: Snapshot of the atomic configurations of shocked quartz (pressure of 56 GPa) during a computer simulation. Upon shock compression, quartz first transforms to an amorphous solid (purple atoms). Thereafter, small domains of different metastable high-pressure phases are formed (different colors of atoms represent different domains) within tens of nanoseconds.

Quartz is one of the most common minerals in Earth’s crust and plays a key role in geology. When meteorites or asteroids strike the Earth, the extreme pressures and temperatures from the impact can permanently alter the structure of quartz. Scientists have studied these structural changes for decades to learn more about past impacts and the consequences in the history of the Earth. However, it has been difficult to understand the mechanisms and transition paths leading to the observed structural alterations in quartz during impacts, since the processes occur on very fast time scales and are thus difficult to observe in experiments in the lab.

In our new study, we have used a powerful new approach: computer simulations based on machine learning. Using a highly accurate model that was previously trained on quantum mechanical data, we simulated computationally the atomic processes in quartz at extreme pressures – conditions similar to those caused by large meteorite and asteroid impacts.

The simulations showed that when quartz is suddenly compressed to 56 GPa (560,000 times atmospheric pressure), it becomes amorphous immediately – meaning its regular crystal structure breaks down into a glass-like form. Then, over several tens of nanoseconds, it crystallizes into a structure known as the “d-NiAs-type”, where oxygen atoms are in a hexagonal close packed arrangement and silicon atoms occupy randomly octahedral voids.

We also explored systematically the transformation of quartz under slower compression from multiple directions – like in certain lab experiments. The simulations show that quartz can transform into another high-pressure structure called “rosiaite-type” silica, when certain strain conditions are fulfilled. In contrast to the processes observed in the shock simulation, this transformation does not require far atomic movements and initial amorphization.

The findings provide detailed insights into the atomic processes of quartz when compressed to high pressures. Particularly, they show that quartz can transform into multiple metastable phases depending on the conditions of the compression. The formation of the high-pressure mineral stishovite, on the contrary, is kinetically hindered. These insights will help to better interpret observations from lab experiments and gain insights into the formation of typical shock features in quartz found in impact sites.

Finally, the study also underlines the importance of computer simulations based on machine learning in revealing how materials behave under extreme conditions and at very fast time scales.

Reference:

Erhard, Linus C., Christoph Otzen, Jochen Rohrer, Clemens Prescher, and Karsten Albe. “Understanding Phase Transitions of α-Quartz under Dynamic Compression Conditions by Machine-Learning Driven Atomistic Simulations.” Npj Computational Materials 11, no. 1 (2025): 58. https://doi.org/10.1038/s41524-025-01542-4.