Meteorite stone

HISTORY OF METEORITE STONE

Meteorites (also called meteoroids according to the term coined by astronomer Hubert Newton) exist everywhere in interplanetary space. These are solid elements from other stars (natural satellites, planets, planetoids, etc.) than the one on which they were found. Thus, in addition to those encountered on our planet, we have been able to observe several on Mars or on the Moon. The vast majority of those that have been observed so far are debris from asteroids. They are fragments deriving from a collision between two stars which most often come from the main belt located between Mars and Jupiter. Their sizes generally vary from a few centimetres to several metres when they enter the upper atmosphere. A meteoroid crosses space then the atmospheric envelope without disappearing at the time of the collision with the surface. However, it disintegrates during its descent and loses a large part of its mass so as to be, at the time of the shock, only a tiny fraction of the object initially entered the atmospheric medium. Thus, it ultimately represents only 1% to 1‰ of its original size. If most of the elements collected come from asteroids, it should nonetheless be mentioned that a few hundred, or less than 0.5%, come from the Moon and Mars. It also looks as though that some are from comets, such as the Orgueil meteorite (Tarn-et-Garonne).

By entering the atmospheric envelope at a speed of several tens of km/s, this rock produces a bright trail: the meteor. Visible only at night, it is a shooting star; visible also during the day, it is then called “racing car”, the latter signifying the passage of a large meteoroid. Generally, the light trail goes out about 20 km above the ground. If the object is not completely volatilised during its passage through the troposphere, it becomes a “meteorite” when it collides with the surface. It can also fragment in the sky, often due to a thermal shock, or at the time of the collision with the ground: we then observe a field of dispersion whose shape depends on the location of the fragmentation (sky or ground). These rocks from elsewhere are classified differently by meteoritologists and meteorite hunters depending on whether they are elements whose fall has been observed or elements discovered by chance. The Meteoritical Society regularly publishes a list of the meteorites analysed during the year. Around 60,000 of them were thus classified in 2018. This number is growing by around 1,500 per year.

METEORITE STONE: BETWEEN THE SACRED AND SCIENCE

Over the millennia, the perception of meteorites has changed. Linked first with the sacred, they have gradually become an important matter of science. In ancient times, many civilisations revered these stones fallen from the sky. The light produced during the crossing of atmospheric gases, sometimes accompanied by sound manifestations, was always an extraordinary spectacle. Exacerbating the imagination and human emotions (fear, adoration, respect), these extraterrestrial materials were sought after: they were sacred, denoting divine power or authority. They were, at that time, used during religious ceremonies, like the Omphalos of the Temple of Apollo in Delphi or the Black Stone in Mecca. Since prehistoric times, men have exploited these strange rocks whose high iron content made it possible to make weapons and jewellery. This has been observed on all continents. The Inuit would have been the first to use them, at least according to our current knowledge. Indeed, the Iron Age of these people would date from the arrival of the meteorite from Cape York (Greenland) 10,000 years ago: archaeologists have found extraterrestrial iron shards in spears of harpoons and blades of knives. In ancient Egypt, meteoric iron was also used, as evidenced by the iron dagger discovered in the sarcophagus of pharaoh Tutankhamun. Meteoric iron spears have also been found in ancient Italy.

Quite a few very ancient literatures mention the existence of these extraterrestrial rocks. In ancient China, it was customary for authors to record the descent of these rocks without mentioning their source. Around -450 BC. AD, the pre-Socratic philosopher Anaxagoras was the first to hypothesise about the extraterrestrial origin of these rocks, although his hypothesis was incorrect since he attributed them to the sun. 1500 years later in Central Asia, the polymath Avicenna claims that stone rocks and iron rocks fall from the sky; he performs fusion experiments with these elements in order to infer the metallic composition.

Yet, the peoples of the Middle Ages continued to venerate these rocks from elsewhere; the Christian church then orders the destruction of what it considers to be pagan symbols. Aristotle’s astronomical theories that the Earth is at the centre of a universe with well-defined contours are valued by the Christian church and prevail for many centuries. These extraterrestrial ores are thus reduced to the rank of optical illusions, metallurgical artefacts or even atmospheric or geological phenomena. Having no official name, they were named “thunderstone”, fireball, Uranolith, etc.
In ancient and medieval stories, the arrival of meteorites was very often associated with superstitions, miracles or prophecies, so European scholars have long viewed these rocks with scepticism. Until the 18th century, they refused to examine the possibility that these stones could originate from space. Some specimens have been observed, but their studies revealed that they were in fact fossils or common rocks (marcasite, pyrite, etc.), even prehistoric tools that we imagined then forged by lightning. In 1676, the mathematician John Wallis witnessed a meteor shower; he then hypothesised that these could come from comets having penetrated the atmosphere. A century later, in the 18th century, three meteorite stones were the subject of scientific analysis; the botanist Fougeroux de Bondaroy and the chemists Cadet de Gassicourt and Antoine Lavoisier, all three members of the Academy of Sciences, are the first to carry out a chemical analysis of this type of stone, but they wrongly conclude that it is of purely earthly elements. In 1769, Antoine Lavoisier hypothesised that the meteoritic rock is formed by lightning during a thunderstorm, then the doctor Joseph Izarn suggests that this formation is done from the clouds. In 1801, the French mineralogist Eugène Louis Melchior Patrin assumed that a meteorite was formed by the combination of gaseous molecules, themselves formed by the circulation of gaseous fluids in the atmosphere. This hypothesis was extensively accepted in the 18th and 19th centuries.
However, as early as 1794, the German physicist Chladni introduced the idea of an extraterrestrial source. The mineralogical and chemical analysis of several meteorites carried out by the British Edward Charles Howard and the French Jacques Louis de Bournon highlights the chondrules (characteristic elements of meteoritic rocks similar to grains and composed mainly of silicates), which supports the thesis of an interstellar provenance. In 1803, following the arrival of the L’Aigle meteorite, the chemist Jean-Antoine Chaptal, then Minister of the Interior of Napoleon Bonaparte, ordered a very complete report from the physicist and astronomer Jean-Baptiste Biot, member of the ’Academy of Sciences of Paris. This report marks the start of the scientific study of meteorites. In 1833, the American astronomer Denison Olmsted definitively invalidates the theory of a terrestrial formation of meteoritic rocks by observing that the radiant of the shower of shooting stars Delta Leonides does not follow the rotation of the terrestrial globe. At the end of the 19th century, the classification of these rocks became systematic due to the work of French geologist Auguste Daubrée. Nonetheless, several scholars in favour of the catastrophist theory, including Jean-Baptiste Biot, Siméon Denis Poisson, John Lawrence Smith, still support Pierre-Simon de Laplace’s hypothesis that meteorite stones originated from lunar volcanoes. Still, more and more scientists are joining the extraterrestrial theory put forward by Chladni. Interest in these rocks continues to grow and, in order to facilitate their studies, numerous collections were formed from the middle of the 19th century in natural history museums, notably those in Paris, London and Washington which today hold the most important meteorite stone collections in the world. We then admit the existence of impact craters. If Chladni’s hypothesis is well established, the interstellar or interplanetary origin of these rock elements continues to be debated until the 1950s, when it is recognized that asteroids are the main source of meteorite stones. Then, during the 1980s, meteoritic rocks of lunar and Martian origin were discovered.

PRESENT-DAY STUDIES ON METEORITE STONE

It only took a few decades for scientific progress to revolutionise our knowledge of the solar system. In fact, laboratories are carrying out increasingly accurate analyses and astronomical observations are becoming more and more accurate. In addition, space exploration makes it possible to visualise other stars and sometimes even to bring back samples to study them. The radiochronology used to date meteorites stones very accurately (207 Pb-206Pb) including plasma mass spectrometers and secondary ionisation (SIMS). The first successful dating took place in 1956: The American geochemist Clair Cameron Patterson estimated the age of a ferrous meteorite at 4.55 billion years, that is, the age of the solar system. Since then, the knowledge of our universe has not stopped progressing thanks to the study of these rocks. It is the assessment of the various minerals contained in a stony meteorite (primitive meteorite, also called chondrite) which enables to highlight that the minerals forming a chondrite are similar to the minerals which one finds on a terrestrial planet. This means that a chondrite is composed of particles of iron and nickel (as in a tellurian nucleus) and silicates identical to those found in the earth’s crust and mantle. Cosmochemists seek to deepen this knowledge to better explain the planetary distinction, that is, the fact that some stars of important dimensions are formed with several layers of different densities, unlike comets, satellites and asteroids small dimensions.

Chondrites are classified according to the distance between their place of formation and the sun. Some carbonaceous chondrites, which are supposed to originate from comet nuclei, have been analysed chemically: they contain amino acids, elementary links in life. This discovery supports the theory of panspermia which suggests that the living organisms present on Earth initially come from extraterrestrial places, although the “primitive soup”, experiment initiated by the American biologist Stanley Miller, tends to show that life has just as could have appeared without extraterrestrial “contamination”. Meteoritic rocks from Mars provide valuable information on Martian geology even though no sample of Martian soil has yet been announced (however, space missions are already scheduled for this purpose). Although this type of rock is very uncommon, research organisations like ANSMET have made it possible to discover a few specimens, thus enabling scientists to acquire new knowledge about the red planet.

Equally rare, meteorites from the Moon allow scientists to study this satellite, since not all of them can work directly on the lunar samples reported between 1969 and 1972 by the missions of the Apollo programme. These rocks help to deepen research around the history of the lunar formation. The creation of the satellite would come from a collision between the Earth and Theia, a star the same size as Mars. Indeed, the Moon would result from an agglomeration of fragments of the tellurian mantle which remained in orbit following the collision. Radioactive isotopes of Aluminium 26Al and iron 60Fe have been found in meteoritic inclusions dating from the beginning of the solar system. The presence of these isotopes associated with the astronomical observation of young stars facilitated the representation of the environment of the primitive sun. It has been deduced that three generations of stars, resulting from gas compression during shock waves generated by supernovae (Little Bang theory), would be at the origin of the solar system, via the creation of a gigantic molecular cloud.

IMPACTS AND FLOWS OF METEORITE STONE

According to estimates, the Earth sweeps 100 tonnes of interplanetary matter daily, which means that about 100 million meteorites enter our atmosphere every day. They are mainly grains of dust of less than 0.1 mg. Most of these elements are micrometeoroids, the consistency of which is similar to that of cigarette ashes, and are consumed during the passage of atmospheric gases. Thus, only six tonnes of meteoritic elements reach the ground daily. Each year, 40 tonnes of meteoric bodies from 10 g to 100 kg and 15,000 to 20,000 tonnes of micrometeorites (up to 50,000 to 100,000 tonnes with interstellar dust) pass through the atmospheric envelope each year. The most substantial specimens nevertheless lose 80% of their mass during their descent through the different gas layers. Beyond 10 − 14 kg, these dusts become micrometeorites and hit the ground in the form of grains of sand; those measuring 10 − 14 kg or less are volatilised without being totally destroyed and their minerals aggregate to fall very slowly. Most of these elements are destroyed in blocks as they descend to the surface, thus limiting the number of large impacts. The number of rocks that reach the ground the size of a tennis ball is estimated to be around 500 each year.

Fragments of very small diameters are therefore much more likely to touch the ground in the form of tiny grains: it is estimated that one falls by 1 µm in diameter every 30 µs, one by one millimetre every 30 s, one of one metre every year, one of 50 m every century, one of 100 m every 10,000 years, one of a kilometre every million years and one of 10 km every 100 million years. A meteoric element weighing more than 10 g reaches the surface every 6 to 30 minutes, which makes about 18,000 to 84,000 elements per year. If 2,000 to 5,000 meteoritic rocks of more than one kilogram strike the ground yearly, 75% vanish due to weather conditions or the place of landing (ocean, desert); among the 25% that do not disappear, few are found. On average, only 5 to 25 falls are observed annually and 2 to 5 impacts are discovered.

The occurrence of substantial rocks fallen from the sky is very unusual: only two have been mentioned in human history. Depending on the collision point, this creates large craters or tsunamis. The speed at which an interstellar fragment penetrates the atmospheric envelope varies from 11 km to 72 km/s. The atmospheric friction on these particles causes a strong heating and the emission of a glowing light, giving birth to the meteor (shooting star or racing car depending on the size). Then, atmospheric friction gradually slows it down, reaching the point of maximum deceleration (called delay point) at an altitude of about 20 km: the light trail then goes out. Finally, the Earth’s gravitational force again increases the speed of fall which can reach up to around 90 m to 180 m/s when it strikes the ground. However, those that weighs several tonnes or more are slowed down less significantly and their speed at the time of the collision is much faster. Estimates state that the number of deaths caused annually by an extraterrestrial unit is about 90. Prior to 2015, no human deaths were reported to be caused by space rock; if three cases were reported during the 19th century, no serious scientific study was done at the time to validate this hypothesis. In 2016, a bus driver from southern India died after falling from a carbonaceous chondrite-like rock: according to Indian scientists, it was the first known death with meteoritic causes. During the impact with the ground, the energy released can have serious direct and indirect consequences: very large fires, reactivation of volcanoes, modification of the climate by the dispersion in the atmosphere of very many particles, etc. According to the American physicist Luis Walter Alvarez, the dinosaurs’ extinction is due to a meteoritic hit. Astronomers therefore monitor space. They counted 900 extraterrestrial objects with a diameter of 1 km to 10 km that can represent a danger for our planet. Most of them are in the main belt between Jupiter and Mars. Some of the elements of this belt can reach 1,000 km in diameter. Scientists estimate that 70 of them are likely to reach us in the 21st century. All have a diameter of less than 1 km, but the consequences of a fall could be particularly significant and irreversible, because the energy released during such an event would be equivalent to the explosion of all the nuclear weapons available in the world, or a power of 10,000 megatons of TNT explosives! However, such a collision is highly unlikely since this risk is estimated at 1/12,346,000.

ORIGIN AND COMPOSITION OF THE METEORITE STONE

Rocks from space result from fragments caused by a collision between two stars or released by disintegration when a comet passes very close to the sun.
The terms to define these rocks from the sky were academically defined in 1958 by the International Astronomical Union :

• meteorite: fragment of meteoroid having reached the earth’s surface without being destroyed during its passage through the atmosphere or at the time of impact ;
• meteoroid: object which moves in the interstellar medium and whose size is smaller than an asteroid and larger than a molecule or an atom.

The dimensions of the second were specified in 1995 by the Royal Astronomical Society: its size is between 100 µm and 10 m. Below 100 µm, we speak of interplanetary dust, because its mass is too small to generate a shooting star; beyond 10 m, we speak of near-Earth objects (minor planets or comets) whose mass is sufficient to reflect light, such as the stars visible through the telescope. The collision with a NEO could create a significant change on Earth, of winter impact type (drop in global temperature). Such a collision with a NEO with a diameter greater than 2 km could even cause a biological crisis (massive extinction resulting in the disappearance of 75% of animal and plant species). However, the limits given by the Royal Astronomical Society evolve with scientific and technological progress. Indeed, the telescopes of the GEODSS, an American optical surveillance network, are so powerful today that they make it possible to observe stars less than 10 m away. In addition, scientists have realised that particles of less than 100 µm, sometimes as small as 10 µm, are able to produce a meteor, the light trail depending on several parameters (speed, density, structure, angle of entrance). The lower and upper limits are therefore constantly reviewed.

For their part, meteorite rock hunters have adopted a much more practical definition which depends on the manner in which these fragments are collected and their size (from 1 cm to 100 m). Taking into account the current power of observation instruments and the recent discovery of shards from the Moon and Mars have allowed a new definition: a meteorite is an element from a celestial body, it is natural and solid, it measures more than 10 µm, it was transported naturally after having escaped the gravitational attraction of its parent body and its trajectory crossed a natural or artificial body of dimensions larger than its own. After having penetrated the gaseous envelope of the celestial body, it reached its surface without having completely volatilised, even if it was altered during the atmospheric crossing or the landing. It remains a meteorite as long as its initial structure remains or its minerals have not disappeared. However, if it aggregates to another rock of higher mass, it no longer has its own definition. As for the meteoroid, it now measures between 10 µm and 1 m and moves in the interplanetary medium. It can be a full body or a fragment of a celestial body. It should be noted that between 100 μm and 2 mm, we speak of micrometeorites and micrometeoroids. Extraterrestrial rocks are named after the place near which they fell or were found (city, region, etc.). If several of them were found in the same place, then the name is followed by a letter or a number allowing the distinction between each element. The Meteoritical Society gives the official name to each of these rocks. An abbreviation or a nickname can sometimes be given in addition to the official name, as is the case for example of Black Beauty, a Martian meteoritic rock found in Africa whose official name is NWA 7034.

PROPERTIES AND PROPERTIES OF METEORITE STONE IN LITHOTHERAPY

THE VIRTUES AND PROPERTIES OF METEORITE STONE ON THE MENTAL PLAN

The metallic meteorite stone is particularly appropriate for people who wish to acquire more willpower and perseverance. It has an energy of materialisation and incarnation that accompanies people in their projects. This mineral brings a precious and essential help to those who wish to carry out their projects.

This rock is also very interesting for working in the context of meditation. All of its varieties lend themselves to meditative work. It brings us closer to the birth of the universe and the Big Bang. It initiates a journey through time and space, in search of the divine. This intimate exploration is done in several stages which it is necessary to memorise well in order to return there, session after session. This allows you to gradually go deeper in this inner journey and progress at your own pace. Before starting this quest, it is, however, necessary to secure yourself by anchoring yourself at foot level; to do this, we will place black tourmalines (large schorls) at the level of the arch of the foot. This rock from space helps us to comprehend that we do not own the Earth, but that we are only passing through it. It inscribes in the wearer the need to respect it. Nowadays, meteoritic glasses are well known in lithotherapy. Formed during the collision with the ground, these stones belong to the tektite family, which also includes the beneficent Moldavite. Their journey to reach us has brought them to bear phenomenal temperatures and pressures, thus acquiring particularly fascinating and useful properties in lithotherapy.

THE PHYSICAL PROPERTIES OF METEORITE STONE

The meteorite stone facilitates the assimilation and integration of iron by the body. Placed near the heart and the fold of the groin, ferric meteorite strengthens the immune system and protects against colds. Rich in iron and nickel, this rock acts similarly to magnetite, but in a more spectacular way. Its magnetism is very powerful, far beyond that of ferrous minerals, including magnetite.