Living beings have played a key role in the formation of almost half of the mineral species on Earth, while water is responsible for more than 80% of mineral diversity, Figures that have been revealed for the first time thanks to two studies published last Friday detailing the origins and diversity of all known minerals on Earth.
The 15-year study, led by the Carnegie Institution for Science, is a landmark work that scientists say will help reconstruct the history of life on Earth, guide the search for new minerals and ore deposits, predict possible characteristics of future life and will help the search for habitable planets and extraterrestrial life.
“Half of all known mineral species on Earth have been formed through biological processes. And a third of those, have only been able to form thanks to life. We do not know of any other way in which they would have been created,” Robert Hazen told Efe.
“It’s a truly amazing statement that just 20 years ago I would have been called crazy,” continues Hazen with a laugh.
Hazen is a mineralogist and astrobiologist at the Carnegie Institution of Washington, co-author of the two studies published in the journal American Mineralogy along with Shaunna Morrison of Earth and Planets Laboratory. The Russian scientist Sergey Krivovichev and the American Robert Downs have also collaborated in one of the studies.
“Types of minerals” amounts to more than 10,500
According to the press release from the Carnegie Institution of Washington, if the genesis of minerals is taken into account, the number of “mineral types” – a newly coined term – amounts to more than 10,500, a number that exceeds 75% of the approximately 6,000 mineral species recognized by the International Mineralogical Association (AIM) based solely on crystal structure and chemical composition.
Hazen and Morrison took advantage of the pandemic to complete a 15-year work that studied the 6,000 known mineral species, and approved by the AIM, in order to determine each of the methods by which they were formed.
“I had no idea what to expect because we didn’t know how many training methods there were. It could be 10 or it could be 200. And after analyzing thousands of studies, we have discovered 57 varieties in the formation of minerals”, explains Hazen.
The scientist gives as examples of these formation methods the electrical discharges of lightning, meteorite impacts and the cooling of volcanic magma. High temperatures and pressures also produce metamorphosis.
Pyrite is the mineral that can be formed with the largest number of methods, exactly 21, in some cases with the help of microbes and in others with the absolute absence of life. Diamonds, on the other hand, can be created from nine different paths.
These almost 60 methods of mineral formation can be summarized into three processes: physical, chemical and biological.
Water and the diversity of minerals on the planet
“More than 80% of the minerals present on Earth were mediated by water, so this element is essential to explain the diversity of minerals on the planet,” says Hazen.
The need for the existence of water would be one of the reasons why Earth’s mineral diversity is much greater than on the Moon, Mercury, and even Mars, which have fewer mineral species.
But almost as important as the role of water has been that of biological processes.
“A third of the minerals on Earth could not have been formed without biological processes,” continues the mineralogist.
For example, without the photosynthesis of plants, the planet would not have had an atmosphere rich in oxygen, an element that has allowed the formation of some 2,000 minerals, according to the authors of the study.
New way of classifying minerals?
As a result of their discovery, Hazen and Morrison have proposed that the way of classifying minerals be modified so that, in addition to considering their crystalline structure and chemical composition, their genesis is incorporated.
“The AIM system is very efficient because it uses as little information as possible to describe the mineral species. In the evolved system we propose, each mineral is a time capsule, it contains its entire history that tells us where it came from, when, how it was formed, and how it fits into the evolution of the planet,” he says.
Hazen adds that including the origin and evolution of minerals, and not just their crystalline structure and chemical composition, changes the view of the diversity of minerals on the planet.
Another revelation of the studies is the disproportionate role that 41 rare elements (including arsenic, cadmium, gold, mercury, silver, titanium, uranium or tungsten) have in the formation of 42% of the minerals on Earth.
“The presence of a single atom of one of these 41 elements for every 10,000 atoms in a rock produces 42% of all the minerals on the planet. It seems to me something incredibly wonderful”, ends by pointing out the American scientist. (YO)