Calcium magnesium carbonate, with the chemical formula CaMg(CO3)2, comprises about 2% of the Earth’s crust, taking hundreds of millions of years to form naturally.
It took scientists nearly two centuries to recreate it in the laboratory. Experts even dubbed this challenge as the “Dolomite Problem”, highlighting the scientific hurdles in reproducing this mineral in a lab environment.
A study published in the journal Science, a collaboration between the University of Michigan (UM) and Hokkaido University in Sapporo, Japan, seems to have tackled this geological puzzle by utilizing proprietary software and dissolving imperfect crystals with an electron beam.
Dolomite is often found in rocks over 100 million years old.
“Previously, those wanting to create perfect crystals always tried to follow a very slow process. However, our theory suggests that you can create them quickly if you periodically eliminate defects during development,” said Wenhao Sun, a scientist at UM and the study’s author, in a press release. “If we understand how dolomite develops in nature, we can devise new strategies to enhance the crystal growth of modern technology materials.”
Dolomite is typically found in rocks over 100 million years old, indicating that this mineral takes a substantial amount of time to form. According to researchers, this slow growth rate may be attributed to the formation process of dolomite’s crystal structure.
The formation of this mineral is created by alternating layers of calcium and magnesium. In aquatic environments, these elements often combine randomly in incorrect positions, thereby hindering the formation of dolomite. While the Earth has almost limitless patience for slow development (for instance, only one layer of dolomite is formed every 10 million years), humans, with relatively shorter lifespans, do not have the same luxury.
To find ways to accelerate the natural process, scientists needed to understand how these defects adhere to the surface of dolomite. According to one researcher, this typically would take thousands of hours on supercomputers, but UM’s proprietary software employed a new technique to complete these simulations in just “2 milliseconds on a desktop computer.”
“Our software calculates the energy for several atomic arrangements, then extrapolates to predict the energy for other arrangements based on the symmetry of the crystal structure,” said Brian Puchala, a collaborative researcher at UM and one of the main developers of the software.
Next, scientists from Hokkaido University used electron microscopy to fire electrons that split water, generating acid that could dissolve the crystals. Each dolomite sample was placed in a calcium/magnesium solution and pulsed with an electron beam 4,000 times over two continuous hours. The resulting acid effectively dissolved all defects and allowed the dolomite to grow about 100 nanometers. This is equivalent to approximately 300 layers of dolomite, 60 times the amount previously cultivated in laboratories.
Decoding the secrets of dolomite growth could help scientists in the future understand the geological processes of other minerals, especially those used in semiconductors.
