Dolomite, a calcium magnesium carbonate mineral, is one of the most abundant minerals on Earth, and one of the most paradoxical. It is found in rock formations stretching back hundreds of millions of years, yet it stubbornly refuses to grow in a laboratory, even when all the right ingredients are present. This contradiction, long known in scientific circles as the “dolomite problem,” has puzzled geologists and materials scientists alike since the early 19th century.
The mineral’s importance goes well beyond academic curiosity. Dolomite is used in construction materials like concrete, as well as in manufacturing, batteries, semiconductors, and solar panels. Its inability to be lab-grown has long represented a quiet bottleneck for industries that depend on it. Understanding how to produce it in controlled settings could have wide-reaching consequences for how these materials are made and supplied.
A Crystal That Defies Its Own Abundance
Dolomite forms over geological timescales through a process that is as slow as it is fragile. According to Popular Mechanics, most dolomite originates from ancient seabeds: when creatures living in primordial seas died, their skeletal remains drifted to the ocean floor and were compressed under extreme pressure for eons, eventually forming limestone. When magnesium-rich water coursed through that limestone, it would recrystallize into dolomite. Outside of these ancient formations, newer growth is exceptionally rare.
Dolomite crystal structure and growth surface – © Journal Sciences
The root of the problem lies in chemistry. Dolomite crystals grow when atoms attach themselves to the surface of an existing crystal in a precise order. Magnesium and calcium, when compressed together, tend to attach to previous layers at random, creating structural defects that slow growth to a near halt. Without the intervention of shifting tides or rainfall, which dissolve and wash away misplaced atoms, it would take roughly 10 million years to form a single layer of dolomite.
Two Centuries of Failed Experiments
Every laboratory attempt to grow dolomite over the past 200 years has ended in failure. As Wenhao Sun, a materials scientist at the University of Michigan’s Predictive Structure Materials Science (PRISMS) Center who led the study recently published in the journal Science, explained: “The apparent contradiction between the massive deposits of dolomite in nature and its inability to grow from supersaturated solutions near ambient conditions is a long-standing mystery known as the ‘dolomite problem.’”
Dolomite step-edge growth and ordering through dissolution-reprecipitation under constant supersaturation as simulated with kinetic Monte Carlo – © Journal Sciences
The frustration runs deep in the scientific record. Crystals need supersaturated solutions, liquids containing high concentrations of the required elements, to form. Yet dolomite consistently refused to precipitate even in heavily supersaturated lab solutions at ambient temperatures. One particularly grim experiment attempted to grow dolomite from a solution saturated a thousand times over. That experiment failed, and ran for 32 years before researchers gave up.
Previous theoretical frameworks trying to explain the mineral’s stubborn behavior only compounded the confusion, offering explanations that could not be translated into workable solutions.
How a Blinking Electron Beam Finally Did the Job
The breakthrough came from combining computational modeling with an unexpected experimental technique. Sun and the PRISMS team trained software to simulate dolomite formation by calculating the energy required for specific atomic arrangements, then using that data to anticipate the energy demands of future arrangements.
The role of supersaturation fluctuations in accelerating dissolution-reprecipitation processes in dolomite ordering – © Journal Sciences
When the simulation was run at constant supersaturation, it reproduced the same familiar structural defects. The team then modeled fluctuating supersaturation levels, mimicking the natural conditions found in coastal environments where dolomite deposits are typically located, where rainfall periodically dilutes the solution and evaporation allows growth to resume.
To observe this actually happening, the PRISMS team joined forces with researchers Yuki Kimura and Tomoya Yamazaki from Hokkaido University, who had identified an unusual asset: the electron beams used by transmission electron microscopes for imaging can split water, producing an acid corrosive enough to dissolve crystal defects.
In situ liquid cell TEM images of dolomite crystal growth – © Journal Sciences
What normally ruins imaging turned out to be exactly what dolomite growth needed. The two teams exploited this by repeatedly pulsing the electron beam at the solution over two hours, zapping away misplaced atoms as they appeared.
As Sun put it, “defective regions are higher in energy than pristine regions and thus will dissolve faster and grow slower, which over time results in a net flux of atoms from defective to pristine sites. By deliberately introducing periods of mild undersaturation, one can facilitate the dissolution of defects, whose dissolution would otherwise proceed very slowly under constant high supersaturation.”
The result was the successful growth of 300 layers of dolomite, still invisible to the naked eye at roughly 100 nanometers, or about 1/250,000th of an inch, but a dramatic leap beyond all prior experiments, none of which had ever exceeded five layers.