Scientists may have discovered how gypsum, a mineral on Earth's surface, manages to form. While gypsum can be created on Earth, understanding this creation process may tell scientists a bit more about water on Mars.
Gypsum is an important mineral on our planet. It's used extensively as the commercial construction material called Plaster of Paris. In all, there's a global production of the mineral of about 100 billion kg per year. And while it's found on Earth, it can also be found on Mars. Until now, though, scientists weren't sure how gypsum grew from ions in solutions.
Gypsum forms from a concentrated aqueous solution of calcium sulfate. In the past, this formation was thought to be a simple, single-step process. However, it appears as if the creation of gypsum is a bit more complex. Scientists have found that it's a four-step process.
In order to get a better look at gypsum's creation, the researchers used in situ and time resolved synchrotron-based X-ray scattering. This allowed them to actually quantify each of the four steps of the formation process.
In the first step, tiny, three-nanometer-long particles form the primary building blocks. In the second step, these blocks arrange themselves into domains. In stage three, they form large aggregates, and in stage four, well-defined primary species begin to grow in these aggregates. In other words, crystals of gypsum are created.
"This is a multi-billion-dollar industry, but basic geochemistry behind the fundamental process has not been understood," said Thomas Stawsky of the University of Leeds, lead author of the new study. "Previous attempts to understand gypsum formation depended on sampling from the solutions in which the mineral was formed and drying, so it was never clear if what we were seeing was an artefact of the process. It's like looking at an ancient mummy, you see the results of the drying process, but that gives you no real understanding of the recently-dead pharaoh they started out with. Now we have a clear idea of the process."
But how will this tell researchers about Mars? Gypsum is naturally found on the Red Planet. This means that the researchers can apply their findings to see how it formed and what hydrological conditions may have been like on Mars during the formation of its gypsum. This, in turn, will give researchers a better understanding on the planet's past climate.
The findings were published in the April 1 issue of the journal Nature Communications.
