The genesis of minerals inspires a new classification

The beverage, sometimes called “fool’s gold” due to its brilliance and lack of value, is the mineral that comes from the most different ways, up to 21 ways: at high and low temperatures, with and without water, by microorganisms or without them, through meteorites, volcanoes, by pressure between rocks or processes associated with mining, among others. However, in any case, its crystal structure and chemical formula (FeS2) it is the same.

It is one of about 5,800 mineral “species” recognized by the International Mineralogical Association (IMA)for its acronym in English), which classifies them according to their Chemical composition there crystallographic structure. But today, after 15 years of work, scientists from Carnegie Institute of the United States proposes a third criterion: its Genesisthat is, how these minerals were formed.

When considering this novel aspect, the same mineral can have several different genetic mechanisms, and of the nearly 6,000 known minerals, it is passed down to more than 10,500 “types of minerals” – this is the new concept – different.

The bone diamondsCarbon compounds, for example, have arisen in at least nine ways, including condensation in the atmospheres of ancient stars, by meteorite impact, or under very high pressures and temperatures deep within the Earth.

The new proposal of classify types of minerals according the mechanisms that gave rise to them throughout the more than 4.5 billion years of history of our planet, and even before, has been the subject of two articles in the journal American mineralogist.

“At this time, we are not asking the IMA to support this alternative approach, but I suspect it may happen in the future,” the lead author told SINC. Robert Hazen, which specifies that it is a question of supplementing what is already used: “It should not replace the effective, simplified and essential system of the International Association of Mineralogy. It uses minimal (bit) information to differentiate each mineral species, but we encompass all non-ideal, messy, and information-rich physical and chemical attributes that, taken together, preserve a record of that mineral’s history. “

“In some cases,” he continues, “these attributes unequivocally indicate a distinctive environment, such as a star’s atmosphere, magma crystallization, aqueous weathering, or lightning. We can apply methods cluster analysis or groups to correlate all messy data with these environments. In other cases, it will take working closely with geologists to unravel the origin, and it will be difficult to standardize, but it’s also a great opportunity to learn more about the history of our planet.”

Based on large freely accessible mineral databases ( there, as well as thousands of surveys of the geology of the places in the world where they are found, the authors identified 10,556 combinations of different types and drive modes.

57 different recipes, many with water and living things

The results show that the minerals emerged in one or more ways among 57 different possibilities, for example, crushed at high pressure, fired at high temperature or condensed (direct transition from gas to solid) in volcanic fumaroles.

Among the species approved by the IMA at the time of the analysis, 3,349 (59%) were derived from a single route, 1,372 (24%) by two different routes, 458 (8%) by three, and the remainder, 480 (8%), in four or more ways.

Nine minerals are born by 15 or more processes physical, chemical and/or biological, from almost instantaneous formation by the impact of lightning or a meteorite, to changes caused by interactions between water and rock, or transformations at high pressures and temperatures over millions of years.

Another of the relevant conclusions of the studies, in which the researcher also took part Shaunna Morrison of Carnegie and other American and Russian geologists, is that the water it played an essential role in the mineral diversity of the Earth, since it participated in the formation of more than 80% of mineral species.

“This explains one of the main reasons why the Moon and Mercury, and even Mars, have much less variety than Earth,” says Hazen, although, on the other hand, he recognizes the potential offered by the large number of moons and exoplanets. “There are many possible worlds rich in minerals, with their own sets of species and types. Even in our own solar system, one of Saturn’s moons, Titan, has a very different mineralogy”.

Another conclusion is that living organisms played a direct or indirect role in the formation of almost half of the known mineral species, and that a third of the known minerals – more than 1,900 species – formed exclusively as a result biological activities. .

were counted 77 biomineralsformed by a variety of metabolic processes, from corals, shells, nettles and microorganisms, to those containing bones, teeth and kidney stones.

Opalized ammonite, a fine example of a biomineral from Canada. / ARKENSTONE/Rob Lavinsky

72 others of them come from the guano and urine of birds and bats. This list includes the rare destroywhich originates when the penguins pee (order Sphenisciformeshence its name) reacts with clay minerals beneath a colony on Elephant Island, Antarctica.

“And we must not forget the indirect role of biology, such as the creation of a oxygen-rich atmosphere [por parte de microorganismos] which gave rise to 2,000 minerals who wouldn’t have been trained any other way,” says Hazen.

Mineral evolution and the origins of life

The authors point out that the birth of the oceans, the development of continental crust and even the start of an early form of subduction (the process that drives plate tectonics) 4 to 4.5 billion years ago meant that many important mineral formation processes – up to 3,534 species – appeared in the first 250 million years Of the earth.

“If so, most of the geochemical and mineralogical parameters suggested by models of the origin of life would already be present 4.3 billion years ago,” they say. And if life is “a cosmic imperative that arises in everything world rich in minerals and watertherefore these findings support the hypothesis that a dynamic and diverse mineral kingdom rapidly developed on our planet.”

Regarding its possible appearance in other parts of the universe, Hazen points out that, “As for the origins of life, we don’t know enough to predict whether other worlds are better able than Earth to produce biochemistry”.

the planetary geologist Jesus Martinez Frias, from the Institute of Geosciences (IGEO, CSIC-UCM), values ​​the work of his colleague: “These new and interesting articles are in line with his research, where he highlights the links between minerals, life and the geological vitality of our planet. If mineral geodiversity exists on Earth, it is thanks to these interconnections. It is precisely for this reason that astrobiology links the relationship between the possible emergence of life and its subsequent biodiversity with geodiversity, two closely related concepts”.

The example of La Palma

“The Hazen line seems to me very important not only for understanding the mineralogical explosion and the origin of life on Earth – he adds – but also for extrapolating it to other planets and moons. We have an example in La Palma, where we have witnessed a new eruption and over time we will see how these new “virgin” materials (volcanic rocks) will evolve geologically and mineralogically, in their interaction with the atmosphere, the water, the global geodynamic cycle of the Earth and with life itself, transforming itself and giving rise to new ones”.

Beryl, a mineral that contains the element beryllium, comes in many beautiful colors, including emerald (its common name). / ARKENSTONE/Rob Lavinsky

On the other hand, human activities they also influence processes related to mineralogical genesis. Besides accidental creations during mine fires, mankind has made thousands of compounds similar to minerals, although they do not meet the requirements to be recognized by the IMA: building materials, semiconductors, crystals laser, special alloys, synthetic gemstones, plastics. remains…

All are “likely to persist for millions of years in the geological record, providing a sedimentary horizon that marks the so-called Anthropocene“, point out the authors, led by Hazen, who recently received a medal of the International Mineralogy Association at its annual meeting, held this year in Lyon (France).

IMA President and Professor at Peking University, Anhuai Lutoo highlighted their latest papers: “The remarkable work of Hazen and Morrison offers a potential avenue for predictably discovering potential minerals in nature. Minerals may hold the key to reconstructing all past life and predicting future life on Earth,” and understanding their evolution “will provide us with a new way to explore deep space and search for extraterrestrial life and habitable planets in the Earth.” future “.

An assessment of Spain

By Juan A. Morales González, President of the Geological Society of Spain (SGE)

The authors have worked hard and very well to establish a new criterion that has never been used before in mineral classifications: genesis. They propose the concept of “mineral types”, in which the same mineral could have several types if different genetic mechanisms exist to form it. But they do not pretend to propose that each of these possible genesis produces different minerals, since if they had the same composition and the same crystallographic structure, they would be the same. This way, we would go from almost 5,800 minerals to over 10,500 types of minerals.

Aspects to highlight would be the possible biogenic origins of many minerals, as well as the presence of extraterrestrial processes. Note also the existence of genetic mechanisms induced by human activity, such as some linked to mining pollution. In this sense, coal mining has been analyzed, but, curiously, not the genesis associated with contamination in acid mine drainage environments, such as those of sulphide mining. Probably, a large number of new types of minerals would be found in this environment.

Eminent mineralogists, such as the president of the IMA, have praised this new proposal and the enormous work of synthesis carried out by the authors, but they express their doubts as to whether it is a classification that can be used in a simple way for immediate identification, since genetic criteria must be used after in-depth studies. Nor will it be a classification that can be easily learned by students and people outside the world of mineralogy.

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