We know that biological species evolve, but what about minerals? What is the reason for their appearance on Earth and what role could they play in the emergence of life on our planet? We discussed these and many other questions with Sergey Vladimirovich Krivovichev, Corresponding Member of the Russian Academy of Sciences, Chairman of the Kola Science Center of the Russian Academy of Sciences, Head of the Department of Crystallography of Saint Petersburg State University.
─ What is a mineral, a mineral species?
─ All minerals are stones, but not all stones are minerals. The concept of a mineral species is very close to the concept of a biological species, although, of course, the diversity of the mineral world is much poorer compared to the biological world.
According to modern concepts, minerals include natural chemical compounds of a crystalline structure formed during geological and geochemical processes. Mineral is a crystalline compound with a certain chemical composition. For a stone to be called a mineral, it must have an internal crystal structure and a completely clear unique composition. In particular, rocks are formed from minerals, that is, rock is a certain combination of various minerals.
─ When did the first minerals appear?
─ The first minerals were formed when the universe had already cooled down after the Big Bang – at least 300 million years after the beginning of time. At first, there were only atoms, then they began to join, form crystalline compounds. Diamond is considered one of the first minerals that appeared in the universe. As for the Earth, the first mineral crystallization occurred on our planet a little less than 5 billion years ago.
─ What role did minerals play in the origin of life on Earth? Could they become a kind of substrate on which life developed?
─ As we know, there is no life without a cell. Living cell is a unit, or atom, of life. But the big question remains how this cell originated, how the complex molecular genetic apparatus that underlies everything appeared. And, since life appeared at some point, that is, it did not exist in the universe before, we can assume that, of course, it should have arisen on an inorganic, that is, on an inanimate substrate. Many theories somehow connect the origin of life with minerals. Similar studies were carried out abroad, for example, by Cairns-Smith from Scotland. In our country, this question was investigated by academician N. P. Yushkin.
In fact, there is some gap between the living and inanimate nature, and we do not yet know how it was overcome. Take, for example, the role that information processes play in the living nature, I mean the DNA molecule and the direct transmission of information – of course, there is nothing like this in minerals. The connection of the origin of life with minerals is a serious mystery that scientists around the world, including our compatriots, are struggling with.
We were able to show that from the viewpoint of Shannon information – and these are rather rough estimates – the complexity of living systems exceeds the complexity of minerals by at least five orders of magnitude, i.e., by 100,000 times. How was such a huge leap in the complexity of atomic objects made? We don’t know.
─ Tsiolkovsky in his works, for example, said that atoms from inorganic matter would sooner or later, even after millions of years, get into a living organism, and therefore potentially even minerals carry life in them.
─ Yes. While if we recall another our great compatriot, V. I. Vernadsky, he insisted that there had never been any traces of abiogenesis in the Earth history, that is, the emergence of the living from the inanimate. This is called the Redi principle – the living from the living (Latin: Omne vivum e vivo – life comes from the living or the birth of the like from the like).
In general, what is life? There is still no answer to this fundamental question. Not so long ago, two major biological journals, the Journal of Biomolecular Structure and Dynamics, and Origins of Life and Evolution of Biosphere, discussed how to define life. It turned out that there is still no unambiguous definition of life in the world. As, for example, there is no definition of matter.
Therefore, some ideas tell us that life and matter are primary entities. The aforementioned V. I. Vernadsky said a lot about this: according to his hypothesis about panspermia, microorganisms were brought to Earth from somewhere in space, and life is a phenomenon that is not reduced to the inanimate.
And if we recall quantum biology, it says that quantum effects play an important role in the phenomenon of life. We can cite as an example the most interesting works on this topic by Roger Penrose, last year’s winner of the Nobel Prize in Physics. And it is not for nothing that Louis de Broglie, one of the founders of quantum mechanics, spoke about the electron freedom, which is necessary to solve many paradoxes of quantum mechanics.
Unfortunately, science is still facing many unresolved issues. Yes, of course, we already know a lot about how minerals are arranged, how life functions, but what is life? There is no definite answer to this question.
─ Since we are talking about space, what do we know about the Solar System minerals?
─ Meteorite mineralogy is a very interesting, I would say, a special section of our science. And here, of course, we can only guess what is happening, for example, in the asteroid belt, what minerals there are: we can calculate this only by certain spectral characteristics. But as for Mars, the Moon, the situation here is more encouraging. Repeated expeditions to Mars brought data on the mineral evolution of the Red Planet and showed that there are water minerals there, for example, clays and water iron sulfates.
In general, we have no indications yet that there are any special minerals in the Solar System that are not present on our planet.
─ That is, here it is the same as with biological life: minerals in space, most likely, appeared because of the same natural mechanisms as on Earth?
─ Probably, yes. The mechanism of minerals appearance is regulated by the laws of physical chemistry, physics, and chemistry. Here, indeed, there is no such unique complexity and originality that we see in the living systems. Therefore, to form a particular mineral, it is necessary that the appropriate chemical composition of the environment and the appropriate thermodynamic conditions, that is, temperature, pressure, and so on, be gathered together.
─ In one of the online lectures for Saint Petersburg State University, you talked about the concept of mineral evolution. And due to what does the complication of the mineral structure and chemical composition occur?
─ Indeed, the concept of mineral evolution does exist and is actively discussed by scientists. In 2008, this term was introduced into modern intellectual discourse by Robert Hazen, professor at the Carnegie Institution in Washington. By the way, at the last election of the Russian Academy of Sciences, Hazen became a Foreign Member of the Russian Academy of Sciences. He studied mineralogy from the moment of the Big Bang to the present day. And, indeed, he demonstrated that the mineral composition is changing. Our universe is evolving, developing, and, of course, the mineral world is also developing, that is, the world of crystalline substances of natural origin. It is especially interesting to trace how the world of minerals on the planet Earth has changed. The decisive factor in the mineral evolution here was the so-called Great Oxidation Event (about 2.5 billion years ago) when the Earth’s atmosphere changed from a reducing to an oxidizing one and the richest variety of the mineral world that we are currently observing emerged.
Together with the aforementioned Robert Hazen and colleagues from Saint Petersburg State University, we decided to trace and measure the mineral world complexity at different stages of its evolution. We managed to introduce into modern mineralogy and crystallography the methods of measuring the crystal structure complexity and the chemical composition complexity, based on the information theory of Claude Shannon.
Thus, we can give two figures for each mineral, one is the chemical complexity, the other is the structural complexity. Based on Hazen’s lists, i.e., the lists of minerals compiled by him for different geological epochs, we were able to see how the chemical and structural complexity of the mineral world changes in the process of mineral evolution, that is, in the process of geological history. And, indeed, it has been shown that the complexity increases. By the way, there are parallels here with biological evolution, where we also see an increase in the number of species and their complexity.
The measures of complexity in biology are not so unambiguous – there are no universal measures of the living organisms’ complexity, but biologists are working on this. We, in turn, have proposed universal measures of complexity for all minerals.
It turned out that the mineral evolution driver is the complication of chemical differentiation, that is, the chemical composition complication, the crystal structure complication. And what is chemical differentiation? This is when chemical elements begin to gradually separate and concentrate from the initial homogeneous mixture of elements, that is, special conditions are created in certain geological environments, special conditions for the concentration of certain elements.
─ What is the reason for this differentiation?
─ There are many factors. It is very important that the mineral world co-evolves together with the biological world, and quite a lot of physicochemical mechanisms are involved in this process. How does this separation occur, the separation of some elements from others? This can occur because of a decrease in temperature, it can be smelting from melts, for example, when low-melting parts of the rock are melted and removed, carrying with them the elements that are in this low-melting part, and several other factors. There is hydrothermal activity, when, say, some elements are well tolerated in aqueous solutions, and others not so well. That is, during the most diverse physical and chemical processes that we see in inanimate nature, there is a separation of elements and a local concentration of certain elements under certain conditions. This, by the way, is the mechanism of mineral deposits formation.
The mineral world and the biological world are co-evolving, and it is in this close interweaving of mineral, geological and biological processes that the diversity of both the living and inanimate world that we observe today is created.
─ Does anthropogenic activity affect the evolution of minerals?
─ Undoubtedly, there is even such a term – technological mineralogy, which studies minerals formed because of human technical activity. When we blow up the earth, penetrate the subsoil and bring to the surface of the earth what was inside in equilibrium, naturally, some chemical processes occur, as a result of which the system falls into a state of disequilibrium, metals oxidize, dissolve, certain elements are released into the biosphere, etc.
This is especially important for the processes occurring during the development of uranium deposits when uranium is taken out of the mining and can enter the biosphere. We know a lot of cases of such disasters, it is not necessary to go far for an example. Here on the Kola Peninsula, near Monchegorsk, at one time there was just a scorched desert, the landscape resembled the surface of Mars. That is, the Monche Tundra, which was so admired by A. E. Fersman in the 1920s, turned into a lifeless desert.
This catastrophe of Soviet times was associated with acid rain, which fell as a result of processing copper-nickel ores. These acid rains burned all living things in their path. And even now, driving past Monchegorsk, you can sometimes see the same pass in the yellow toxic fog. So, yes, human activity strongly affects mineral evolution, forming new minerals, new phases.
─ Sergey Vladimirovich, you are the chairman of the Kola Science Center of the Russian Academy of Sciences, which is located directly in the Arctic. Tell us more about your center’s work.
─ Our center is not just the only federal research center of the Russian Academy of Sciences, which is located right outside the Arctic Circle, but also the Academy’s oldest regional organization.
The Khibinsky mountain station, which grew into the Kola Science Center, which celebrated its 90th anniversary last year, was created by the work of Academician A. E. Fersman and his colleagues in the mountains on the shore of Maly Vudyavr Lake. The Kola Science Center scientists actively participated in the development and scientific support of the Far North economy. In particular, we are talking about the development of mineral deposits. Our scientific interests include the entire Arctic nature itself, the study and preservation of unique Arctic ecosystems. Since the Soviet years, science and industry in the region have been in close cooperation, and in this sense, the Kola Scientific Center has always been (and remains) a kind of an outpost of science in the Russian Arctic.
Over the past 30 years, of course, a lot has changed, and we are gradually returning to the state of infrastructure and personnel provision that we had in our past. And now the KSC RAS tasks remain the same. These are the study of the Arctic nature and Arctic geology, the mining developments: how to use the mineral raw materials that are extracted in the Arctic zone to create new materials, extract rare and scattered elements, etc. These are environmental issues that are currently at the forefront of science, and humanitarian problems, including the history of the Russian Arctic development, the anthropology of small peoples who have lived in the Far North for centuries, international issues, and, of course, the economy – it is special in the Arctic zone and associated with single-industry towns, population outflow. All these issues are dealt with by separate institutes and departments at the Kola Science Center.
─ Did you want to study minerals since childhood? Which of them are your favorite?
─ We have, in fact, a geological dynasty: my grandfather, father, mother, aunt, and uncle were all connected to geology, to minerals. In this sense, we have a rather unique family. Three minerals were named in honor of our family members: in honor of your humble servant, krivovichevite from the Kola Peninsula; in honor of my father, a famous mineralogist, vladkrivovichevite, found in Namibia; and in honor of my mother, a mineral discovered in Kamchatka, starovaite (her maiden name is Starova). And, as you probably have already guessed, these three minerals are my favorite, because they directly relate to my family.
Of course, I have been fond of mineralogy since childhood, because I grew up surrounded by wonderful shiny stones and very beautiful minerals. My father had a small collection of minerals. And, of course, sometimes I came to visit my father at the Mineralogical Museum of Saint Petersburg State University. I remember from my childhood these sun-drenched shiny auditoria, showcases with beautiful huge stones, sparkling with their facets. It is not for nothing that the great Russian crystallographer, academician E. S. Fedorov, said that crystals shine with symmetry. I think that my strong childhood impressions relate to the correctness of the minerals’ shapes, to their amazing geometry.
Actually, crystallography and minerals are the most real geometry in nature. On the one hand, minerals contain a strong esthetic component, and on the other hand, it is empirical: that is, we are holding a real physical substance in our hands, and not some theoretical concept. I think that this combination of mathematics, rigor, on the one hand, and empiricism on the other, in a sense, formed my scientific worldview.