What types of meteorites are distinguished by chemical composition. Types of meteorites
Meteorites are not large iron, stone or iron-stone space objects that regularly fall on the surface of the planets of the solar system, including the Earth. Outwardly, they are not much different from stones or pieces of iron, but they are fraught with many mysteries from the history of the universe. Meteorites help scientists uncover the secrets of the evolution of celestial bodies and study processes that take place far beyond our planet.
Analyzing their chemical and mineral composition, one can trace the patterns and relationships between meteorites. various kinds. But each of them is unique, with qualities inherent only in this body of cosmic origin.
Types of meteorites by composition:
1. Stone:
Chondrites;
Achondrites.
2. Iron-stone:
Pallasites;
Mesosiderites.
3. Iron.
Octahedrites
Ataxites
4. Planetary
Martian
Origin of meteorites
Their structure is extremely complex and depends on many factors. By studying all known varieties of meteorites, scientists have come to the conclusion that they are all closely related at the genetic level. Even taking into account significant differences in structure, mineral and chemical composition, they are united by one thing - the origin. All of them are fragments of celestial bodies (asteroids and planets) moving in outer space at high speed.
Morphology
To reach the Earth's surface, a meteorite has to make a long journey through the layers of the atmosphere. As a result of a significant aerodynamic load and ablation (high-temperature atmospheric erosion), they acquire characteristic external features:
Oriented-conical shape;
Melting bark;
Special surface relief.
A distinctive feature of real meteorites is the melting crust. In color and structure, it can differ quite significantly (depending on the type of body of cosmic origin). In chondrites it is black and matte, in achondrites it is shiny. In rare cases, the melting crust may be light and translucent.
With a long stay on the surface of the Earth, the surface of the meteorite is destroyed under the influence of atmospheric influences and oxidation processes. For this reason, a significant part of the bodies of cosmic origin through certain time practically no different from pieces of iron or stones.
Another distinctive outward sign, which has real meteorite, is the presence on the surface of depressions called piezoglypts or regmaglipts. Reminiscent of fingerprints on soft clay. Their size and structure depend on the conditions of meteorite movement in the atmosphere.
Specific gravity
1. Iron - 7.72. The value can vary in the range of 7.29-7.88.
2. Pallasites - 4.74.
3. Mesosiderites - 5.06.
4. Stone - 3.54. The value can vary in the range of 3.1-3.84.
Magnetic and optical properties
Due to the presence of a significant amount of nickel iron, a real meteorite exhibits its unique magnetic properties. This is used to verify the authenticity of a body of cosmic origin and allows indirect judgment of the mineral composition.
The optical properties of meteorites (color and reflectivity) are less pronounced. They appear only on the surfaces of fresh fractures, but over time, due to oxidation, they become less and less noticeable. Comparing the average values of the brightness coefficient of meteorites with the albedo of the celestial bodies of the solar system, scientists came to the conclusion that some planets (Jupiter, Mars), their satellites, as well as asteroids are similar in their optical properties to meteorites.
The chemical composition of meteorites
Considering the asteroidal origin of meteorites, their chemical composition can differ significantly between objects of different types. This has a significant effect on the magnetic and optical properties, as well as the specific gravity of bodies of cosmic origin. The most common chemical elements in meteorites are:
1. Iron (Fe). It is the main chemical element. Occurs as nickel iron. Even in stony meteorites, the average Fe content is 15.5%.
2. Nickel (Ni). It is part of nickel iron, as well as minerals (carbides, phosphides, sulfides and chlorides). Compared to Fe, it occurs 10 times less frequently.
3. Cobalt (Co). Not found in pure form. Compared to nickel, it is 10 times rarer.
4. Sulfur (S). It is part of the mineral troilite.
5. Silicon (Si). It is part of the silicates that form the bulk of stony meteorites.
3. Rhombic pyroxene. Often found in stony meteorites, among silicates - the second most common.
4. Monoclinic pyroxene. In meteorites, it is rare and in small quantities, with the exception of achondrites.
5. Plagioclase. A common rock-forming mineral that is part of the feldspar group. Its content in meteorites varies widely.
6. Glass. It is the main component of stone meteorites. Contained in chondrules, and also occurs as inclusions in minerals.
> Types of meteorites
Find out what are types of meteorites: classification description with photo, iron, stone and stone-iron, meteorites from the Moon and Mars, asteroid belt.
Often a common person imagining what a meteorite looks like, thinks of iron. And it's easy to explain. Iron meteorites are dense, very heavy, and often take on unusual and even impressive shapes as they fall and melt in our planet's atmosphere. And although iron is associated with the typical composition of space rocks in most people, iron meteorites are one of the three main types of meteorites. And they are quite rare compared to stony meteorites, especially the most common group of them - single chondrites.
Three main types of meteorites
There is a large number meteorite types, divided into three main groups: iron, stone, stone-iron. Almost all meteorites contain extraterrestrial nickel and iron. Those that do not contain iron at all are so rare that even if we ask for help identifying possible space rocks, we will most likely not find anything that does not contain a large amount of metal. The classification of meteorites is, in fact, based on the amount of iron contained in the sample.
iron type meteorite
iron meteoriteswere part of the core of a long-dead planet or a large asteroid from which it is believed that between Mars and Jupiter. They are the densest materials on Earth and are very strongly attracted to a strong magnet. Iron meteorites are much heavier than most of the Earth's rocks, if you've lifted a cannonball or a slab of iron or steel, you know what I'm talking about.
In most samples of this group, the iron component is approximately 90% -95%, the rest is nickel and trace elements. Iron meteorites are divided into classes according to their chemical composition and structure. Structural classes are determined by examining two components of iron-nickel alloys: kamacite and taenite.
These alloys are complex crystal structure, known as the Widmanstetten structure, named after Count Alois von Widmanstetten, who described the phenomenon in the 19th century. This lattice-like structure is very beautiful and is clearly visible if the iron meteorite is cut into plates, polished and then etched in a weak solution. nitric acid. For kamacite crystals found in the process, the average band width is measured and the resulting figure is used to separate iron meteorites into structural classes. Iron with a thin band (less than 1 mm) is called "fine-structured octahedrite", with a wide band "coarse octahedrite".
Stone view of the meteorite
The largest group of meteorites - stone, they formed from the outer crust of a planet or asteroid. Many stony meteorites, especially those that have been on the surface of our planet for a long time, are very similar to ordinary terrestrial stones, and it takes an experienced eye to find such a meteorite in the field. Recently fallen rocks have a black lustrous surface that was formed by the burning of the surface in flight, and the vast majority of rocks contain enough iron to be attracted to a powerful magnet.
Some stony meteorites contain small, colorful, grain-like inclusions known as "chondrules". These tiny grains originated from the solar nebula, therefore, before the formation of our planet and the entire solar system, which makes them the oldest known matter available for study. Stony meteorites containing these chondrules are called "chondrites".
Space rocks without chondrules are called "achondrites". These are volcanic rocks, shaped by volcanic activity on their "parent" space objects, where melting and recrystallization have obliterated all traces of the ancient chondrules. Achondrites contain little or no iron, making it difficult to find compared to other meteorites, although specimens often have a glossy crust that looks like enamel paint.
Stone view of a meteorite from the Moon and Mars
Can we really find lunar and Martian rocks on the surface of our own planet? The answer is yes, but they are extremely rare. More than one hundred thousand lunar and about thirty Martian meteorites have been found on Earth, and all of them belong to the achondrite group.
The collision of the surface of the Moon and Mars with other meteorites threw fragments into outer space and some of them fell to the ground. From a financial point of view, lunar and Martian samples are among the most expensive meteorites. In the collectors' markets, they cost up to a thousand dollars per gram, which makes them several times more expensive than if they were made of gold.
Stone-iron type of meteorite
The least common of the three main types - stone-iron, accounts for less than 2% of all known meteorites. They consist of approximately equal parts of iron-nickel and stone, and are divided into two classes: pallasite and mesosiderite. Stone-iron meteorites were formed at the border of the crust and mantle of their "parent" bodies.
Pallasites are perhaps the most enticing of all meteorites and are definitely of great interest to private collectors. Pallasite is composed of an iron-nickel matrix filled with olivine crystals. When olivine crystals are clear enough to appear emerald green, they are known as a perodot gemstone. Pallasites got their name in honor of the German zoologist Peter Pallas, who described the Russian meteorite Krasnoyarsk, found near the capital of Siberia in the 18th century. When a pallasite crystal is cut into slabs and polished, it becomes translucent, giving it an ethereal beauty.
Mesosiderites are the smaller of the two stony-iron groups. They are composed of iron-nickel and silicates and are usually attractive. The high contrast of the silver and black matrix, when the plate is cut and sanded, and the occasional blotch, results in a very unusual look. The word mesosiderite comes from the Greek for "half" and "iron" and they are very rare. In thousands of official catalogs of meteorites, there are less than a hundred mesosiderites.
Classification of types of meteorite
The classification of meteorites is a complex and technical subject and the above is intended only as a guide. overview Topics. Classification methods have changed several times over the years. last years; known meteorites were reclassified to another class.
Meteors are particles of interplanetary material that pass through the Earth's atmosphere and are heated to incandescence by friction. These objects are called meteoroids and race through space, becoming meteors. In a few seconds, they cross the sky, creating luminous trails.
meteor showers
Scientists have calculated that 44 tons of meteoritic matter falls to Earth every day. A few meteors per hour can usually be seen on any given night. Sometimes the number increases dramatically - these phenomena are called meteor showers. Some occur annually or at regular intervals as the Earth passes through a trail of dusty debris left by a comet.
Leonid meteor shower
Meteor showers are usually named after the star or constellation closest to where the meteors appear in the sky. Perhaps the most famous are the Perseids, which appear on August 12 every year. Each Perseid meteor is a tiny piece of the Swift-Tuttle comet that takes 135 years to orbit the Sun.
Other meteor showers and related comets are the Leonids (Tempel-Tuttle), the Aquarids and Orionids (Halley), and the Taurids (Encke). Most of the comet dust in meteor showers burns up in the atmosphere before reaching the Earth's surface. Some of this dust is captured by aircraft and analyzed at NASA laboratories.
meteorites
Pieces of rock and metal from asteroids and other cosmic bodies that survive their journey through the atmosphere and fall to earth are called meteorites. Most meteorites found on Earth are pebbly, about the size of a fist, but some are larger than buildings. Once upon a time, the Earth experienced many serious meteor attacks that caused significant destruction.
One of the best-preserved craters is the Barringer meteorite crater in Arizona, about 1 km (0.6 miles) in diameter, formed by the fall of a piece of iron-nickel metal approximately 50 meters (164 feet) in diameter. It is 50,000 years old and so well preserved that it is used to study meteorite impacts. Since the site was recognized as such an impact crater in 1920, about 170 craters have been found on Earth.
Barringer Meteor Crater
A severe asteroid impact 65 million years ago that created the 300 kilometers wide (180 miles) Chicxulub crater in the Yucatán Peninsula contributed to the extinction of about 75 percent of the marine and land animals on Earth at that time, including dinosaurs.
There is little documented evidence of meteorite damage or death. In the first famous case an extraterrestrial object injured a person in the United States. Ann Hodges of Sylacauga, Alabama, was injured after a 3.6 kilogram (8 lb) stony meteorite hit the roof of her house in November 1954.
Meteorites may look like terrestrial rocks, but they usually have a burnt surface. This burnt crust is the result of a meteorite melting due to friction as it passes through the atmosphere. There are three main types of meteorites: silver, stony, and stony-silver. Although most of the meteorites that fall to Earth are stony, more meteorites are found in Lately- silver. These heavy objects are easier to distinguish from the rocks of the Earth than stony meteorites.
This meteorite image was taken by the Opportunity rover in September 2010.
Meteorites also fall on other bodies solar system. The Opportunity rover was exploring different types of meteorites on another planet when it discovered a basketball-sized iron-nickel meteorite on Mars in 2005, and then found a much larger and heavier iron-nickel meteorite in 2009 in the same area. In all, the Opportunity rover discovered six meteorites during its journey across Mars.
Sources of meteorites
Over 50,000 meteorites have been found on Earth. Of these, 99.8% came from the Asteroid Belt. Evidence for their origin from asteroids includes a meteorite impact orbit computed from photographic observations projected back onto the asteroid belt. An analysis of several classes of meteorites showed a coincidence with some classes of asteroids, and they also have an age of 4.5 to 4.6 billion years.
Researchers discover new meteorite in Antarctica
However, we can only match one group of meteorites to a particular type of asteroid - eucrite, diogenite and howardite. These igneous meteorites come from the third largest asteroid, Vesta. The asteroids and meteorites that fall to Earth are not parts of the planet that broke up, but are made up of the original materials from which the planets formed. The study of meteorites tells us about the conditions and processes during the formation and early history of the solar system, such as age and composition. solids, nature organic matter, the temperatures reached on the surface and inside the asteroids, and the shape these materials were brought into by the impact.
The remaining 0.2 percent of meteorites can be divided roughly equally between meteorites from Mars and the Moon. More than 60 known Martian meteorites have been ejected from Mars as a result of meteor showers. They are all igneous rocks that have crystallized from magma. The stones are very similar to those of the earth, with some hallmarks, which indicate a Martian origin. Nearly 80 lunar meteorites are similar in mineralogy and composition to moon rocks from the Apollo mission, but are different enough to show that they came from different parts Moon. Research on lunar and Martian meteorites complements research on the rocks of the Moon by the Apollo mission and robotic exploration of Mars.
Types of meteorites
Quite often, an ordinary person, imagining what a meteorite looks like, thinks of iron. And it's easy to explain. Iron meteorites are dense, very heavy, and often take on unusual and even impressive shapes as they fall and melt in our planet's atmosphere. And although iron is associated with the typical composition of space rocks in most people, iron meteorites are one of the three main types of meteorites. And they are quite rare compared to stony meteorites, especially the most common group of them - single chondrites.
Three main types of meteorites
There are a large number of types of meteorites, divided into three main groups: iron, stone, stone-iron. Almost all meteorites contain extraterrestrial nickel and iron. Those that do not contain iron at all are so rare that even if we ask for help identifying possible space rocks, we will most likely not find anything that does not contain a large amount of metal. The classification of meteorites is, in fact, based on the amount of iron contained in the sample.
Iron meteorites were part of the core of a long-dead planet or large asteroid that is thought to have formed the Asteroid Belt between Mars and Jupiter. They are the densest materials on Earth and are very strongly attracted to a strong magnet. Iron meteorites are much heavier than most of the Earth's rocks, if you've lifted a cannonball or a slab of iron or steel, you know what I'm talking about.
An example of an iron meteorite
In most samples of this group, the iron component is approximately 90% -95%, the rest is nickel and trace elements. Iron meteorites are divided into classes according to their chemical composition and structure. Structural classes are determined by examining two components of iron-nickel alloys: kamacite and taenite.
These alloys have a complex crystal structure known as the Widmanstetten structure, named after Count Alois von Widmanstetten, who described the phenomenon in the 19th century. This lattice-like structure is very beautiful and is clearly visible if the iron meteorite is cut into plates, polished and then etched in a weak solution of nitric acid. For kamacite crystals found in the process, the average band width is measured and the resulting figure is used to separate iron meteorites into structural classes. Iron with a thin band (less than 1 mm) is called "fine-structured octahedrite", with a wide band "coarse octahedrite".
stone meteorites
The largest group of meteorites are stony, they formed from the outer crust of a planet or an asteroid. Many stony meteorites, especially those that have been on the surface of our planet for a long time, are very similar to ordinary terrestrial stones, and it takes an experienced eye to find such a meteorite in the field. Recently fallen rocks have a black lustrous surface that was formed by the burning of the surface in flight, and the vast majority of rocks contain enough iron to be attracted to a powerful magnet.
A typical representative of chondrites
Some stony meteorites contain small, colorful, grain-like inclusions known as "chondrules". These tiny grains originated from the solar nebula, therefore, before the formation of our planet and the entire solar system, which makes them the oldest known matter available for study. Stony meteorites containing these chondrules are called "chondrites".
Space rocks without chondrules are called "achondrites". These are volcanic rocks, shaped by volcanic activity on their "parent" space objects, where melting and recrystallization have obliterated all traces of the ancient chondrules. Achondrites contain little or no iron, making it difficult to find compared to other meteorites, although specimens often have a glossy crust that looks like enamel paint.
Stone meteorites from the Moon and Mars
Can we really find lunar and Martian rocks on the surface of our own planet? The answer is yes, but they are extremely rare. More than one hundred thousand lunar and about thirty Martian meteorites have been found on Earth, and all of them belong to the achondrite group.
lunar meteorite
The collision of the surface of the Moon and Mars with other meteorites threw fragments into outer space and some of them fell to Earth. From a financial point of view, lunar and Martian samples are among the most expensive meteorites. In the collectors' markets, they cost up to a thousand dollars per gram, which makes them several times more expensive than if they were made of gold.
Stony-iron meteorites
The least common of the three main types, stony-iron, accounts for less than 2% of all known meteorites. They consist of approximately equal parts of iron-nickel and stone, and are divided into two classes: pallasite and mesosiderite. Stone-iron meteorites were formed at the border of the crust and mantle of their "parent" bodies.
An example of a stone-iron meteorite
Pallasites are perhaps the most enticing of all meteorites and are definitely of great interest to private collectors. Pallasite is composed of an iron-nickel matrix filled with olivine crystals. When olivine crystals are clear enough to appear emerald green, they are known as a perodot gemstone. Pallasites got their name in honor of the German zoologist Peter Pallas, who described the Russian meteorite Krasnoyarsk, found near the capital of Siberia in the 18th century. When a pallasite crystal is cut into slabs and polished, it becomes translucent, giving it an ethereal beauty.
Mesosiderites are the smaller of the two stony-iron groups. They are composed of iron-nickel and silicates and are usually attractive. The high contrast of the silver and black matrix, when the plate is cut and sanded, and the occasional blotch, results in a very unusual look. The word mesosiderite comes from the Greek for "half" and "iron" and they are very rare. In thousands of official catalogs of meteorites, there are less than a hundred mesosiderites.
Classification of meteorites
Meteorite classification is a complex and technical subject and the above is only intended as a brief overview of the topic. Classification methods have changed several times in recent years; known meteorites were reclassified to another class.
martian meteorites
A Martian meteorite is a rare type of meteor that came from the planet Mars. Until November 2009, more than 24,000 meteors had been found on Earth, but only 34 of them were Martian. The Martian origin of meteors was known from the composition of the isotopic gas contained in meteors in microscopic quantities, the analysis of the Martian atmosphere was carried out by the Viking spacecraft.
The emergence of the Martian meteorite Nakhla
In 1911, the first Martian meteorite called Nakhla was found in the Egyptian desert. The appearance and belonging of the meteorite to Mars was established much later. And they established its age - 1.3 billion years. These stones appeared in space after large asteroids fell on Mars or during massive volcanic eruptions. The strength of the explosion was such that the ejected pieces of rock acquired the speed necessary to overcome the gravity of the planet Mars and leave its orbit (5 km / s). In our time, up to 500 kg of Martian stones fall to Earth in one year.
Two parts of the Nakhla meteorite
In August 1996, an article was published in the journal Science about the study of the meteorite ALH 84001, found in Antarctica in 1984. started new job, centered around a meteorite found in a glacier in Antarctica. The study was carried out using a scanning electron microscope, they revealed "biogenic structures" inside the meteor, which theoretically could be formed by life on Mars.
The isotope date showed that the meteor appeared about 4.5 billion years ago, and having fallen into interplanetary space, fell to Earth 13 thousand years ago.
"Biogenic structures" found on a cut of a meteorite
While studying the meteor with an electron microscope, experts found microscopic fossils suggestive of bacterial colonies composed of separate parts with a volume of approximately 100 nm. Traces of preparations resulting from the decomposition of microorganisms were also found. The proof of the occurrence of a Martian meteor requires microscopic examination and special chemical analyzes. A specialist can testify to the Martian occurrence of a meteor in accordance with the presence of minerals, oxides, calcium phosphates, silicon and iron sulfide.
The known specimens are invaluable because they are typical time capsules from Mars' geologic past. We received these Martian meteorites without any space missions.
The largest meteorites that fell to Earth
From time to time, cosmic bodies fall to Earth ... more and not very much, made of stone or metal. Some of them are no more than a grain of sand, others weigh several hundred kilograms or even tons. Scientists from the Astrophysical Institute in Ottawa (Canada) claim that several hundred solid alien bodies with a total mass of more than 21 tons visit our planet every year. The weight of most meteorites does not exceed a few grams, but there are those that weigh several hundred kilograms or even tons.
The places where meteorites fall are either fenced off or vice versa open to the public so that everyone can touch the extraterrestrial "guest".
Some confuse comets and meteorites due to the fact that both of these celestial bodies have a fiery shell. In ancient times, people considered comets and meteorites a bad omen. People tried to avoid places where meteorites fell, considering them to be a cursed zone. Fortunately, in our time, such cases are no longer observed, and even vice versa - the places where meteorites fall are of great interest to the inhabitants of the planet.
Let's remember the 10 largest meteorites that fell on our planet.
A meteorite fell on our planet on April 22, 2012, the speed of the fireball was 29 km / s. Flew over the states of California and Nevada, the meteorite scattered its burning fragments for tens of kilometers and exploded in the sky over the US capital. The power of the explosion is relatively small - 4 kilotons (in TNT equivalent). For comparison, the explosion of the famous Chelyabinsk meteorite was 300 kilotons in TNT.
According to scientists, the Sutter Mill meteorite was formed at the time of the birth of our solar system, a cosmic body more than 4566.57 million years ago.
On February 11, 2012, hundreds of tiny meteorite stones flew over the territory of China and fell over an area of over 100 km in the southern regions of China. The largest of them weighed about 12.6 kg. According to scientists, the meteorites came from the asteroid belt between Jupiter and Mars.
On September 15, 2007, a meteorite fell near Lake Titicaca (Peru) near the border with Bolivia. According to eyewitnesses, the event was preceded by a loud noise. Then they saw a falling body engulfed in flames. The meteorite left a bright trail in the sky and a plume of smoke, which was visible several hours after the fireball fell.
A huge crater 30 meters in diameter and 6 meters deep formed at the crash site. The meteorite contained toxic substances, as people living nearby started getting headaches.
Most often, meteorites made of stone (92% of the total), consisting of silicates, fall to Earth. The Chelyabinsk meteorite is an exception, it was iron.
The meteorite fell on June 20, 1998 near the Turkmen city of Kunya-Urgench, hence its name. before the fall locals saw a bright flash. The most most of the car weighs 820 kg, this piece fell into the field and formed a funnel of 5 meters.
According to geologists, the age of this celestial body is about 4 billion years. The Kunya-Urgench meteorite is certified by the International Meteoritic Society and is considered the largest of all fireballs that fell on the territory of the CIS and third world countries.
Iron car Sterlitamak, whose weight was more than 300 kg, fell on May 17, 1990 on the field of the state farm west of the city of Sterlitamak. When a celestial body fell, a crater of 10 meters was formed.
Initially, small metal fragments were discovered, a year later, scientists managed to extract the largest fragment of a meteorite weighing 315 kg. Currently, the meteorite is in the Museum of Ethnography and Archeology of the Ufa Scientific Center.
This event took place in March 1976 in Jilin Province in eastern China. The largest meteor shower lasted more than half an hour. Space bodies fell at a speed of 12 km per second.
Only a few months later, about a hundred meteorites were found, the largest - Jilin (Girin), weighed 1.7 tons.
This meteorite fell on February 12, 1947 on Far East in the city of Sikhote-Alin. The bolide was fragmented in the atmosphere into small iron pieces, which scattered over an area of 15 sq. km.
Several dozen craters 1-6 meters deep and 7 to 30 meters in diameter were formed. Geologists have collected several tens of tons of meteorite material.
Goba meteorite (1920)
Meet Goba - one of the largest meteorites ever found! It fell to Earth 80 thousand years ago, but was found in 1920. A real iron giant weighed about 66 tons and had a volume of 9 cubic meters. Who knows with what myths the people living at that time associated the fall of this meteorite.
composition of the meteorite. 80% of this celestial body consists of iron, it is considered the heaviest of all meteorites that have ever fallen on our planet. Scientists took samples, but did not transport the entire meteorite. Today it is at the crash site. This is one of the largest pieces of iron on Earth of extraterrestrial origin. The meteorite is constantly decreasing: erosion, vandalism and Scientific research did their job: the meteor fell by 10%.
A special fence was created around it, and now Goba is known to the whole planet, many tourists come to visit it.
The mystery of the Tunguska meteor (1908)
The most famous Russian meteorite. In the summer of 1908, a huge fireball flew over the territory of the Yenisei. The meteorite exploded at an altitude of 10 km above the taiga. The blast wave circled the Earth twice and was recorded by all observatories.
The power of the explosion is simply monstrous and is estimated at 50 megatons. The flight of a space giant is a hundred kilometers per second. Weight, according to various estimates, varies - from 100 thousand to one million tons!
Fortunately, no one was hurt in this. The meteorite exploded over the taiga. In nearby settlements the window was blown out by the blast.
Trees fell down as a result of the explosion. Forest areas of 2,000 sq. turned into rubble. The blast killed animals within a radius of more than 40 km. For several days, artifacts were observed over the territory of central Siberia - luminous clouds and the glow of the sky. According to scientists, this was caused by inert gases that were released at the moment the meteorite entered the Earth's atmosphere.
What was it? The meteorite would have left a huge crater at the site of impact, at least 500 meters deep. No expedition has been able to find anything like it...
The Tunguska meteor, on the one hand, is a well-studied phenomenon, on the other hand, one of the biggest mysteries. Heavenly body exploded in the air, the pieces burned up in the atmosphere, and no remnants remained on Earth.
The working title "Tunguska meteorite" appeared because this is the simplest and most understandable explanation for a flying ball of fire that caused an explosion effect. The Tunguska meteorite was also called crashed alien ship, and a natural anomaly, and a gas explosion. What he was in reality - one can only guess and build hypotheses.
Meteor shower in the USA (1833)
On November 13, 1833, a meteor shower fell over the eastern territory of the United States. The duration of the meteor shower is 10 hours! During this time, about 240 thousand small and medium-sized meteorites fell on the surface of our planet. The meteor shower of 1833 is the most powerful of all known meteor showers.
Every day, dozens of meteor showers fly near our planet. About 50 potentially dangerous comets are known that can cross the Earth's orbit. The collision of our planet with small (not capable of causing great harm) cosmic bodies occurs once every 10-15 years. A special danger to our planet is the fall of an asteroid.
Chelyabinsk meteorite
Almost two years have passed since the people of South Urals became eyewitnesses of a cosmic cataclysm - the fall of the Chelyabinsk meteorite, which became for the first time in modern history incident that caused significant damage to the local population.
The fall of the asteroid occurred in 2013, on February 15th. At first, it seemed to the people of South Urals that an “obscure object” had exploded, many saw strange lightning bolts illuminating the sky. This is the opinion of scientists who have studied this incident for a year.
meteorite data
A rather ordinary comet fell in the area near Chelyabinsk. Falls of space objects of precisely this nature occur once in a century. Although according to other sources, they happen repeatedly, on average up to 5 times in 100 years. According to scientists, comets about 10 meters in size fly into the atmosphere of our Earth approximately once a year, which is 2 times more than the Chelyabinsk meteorite, but often this happens over regions with a small number of people or over the oceans. At what comets burn down and collapse at a great height, without causing any damage.
The plume from the Chelyabinsk meteorite in the sky
Before the fall, the mass of the Chelyabinsk aerolite was from 7 to 13 thousand tons, and its parameters were presumably 19.8 m. At present, a little more than one ton has been collected from this amount, including one of the large fragments of aerolite weighing 654 kg., Lifted from the bottom of Chebarkul Lake.
The study of the Chelyabinsk mayorite according to geochemical indicators revealed that it belongs to the type of ordinary chondrites of the LL5 class. This is the most common subgroup of stony meteorites. All currently discovered meteorites, about 90%, are chondrites. They got their name due to the presence of chondrules in them - spherical melted formations with a diameter of 1 mm.
The readings of infrasound stations indicate that at the moment of strong deceleration of the Chelyabinsk aerolith, when about 90 km remained to the ground, a powerful explosion with a force equal to the TNT equivalent of 470-570 kilotons, which is 20-30 times stronger than the atomic explosion in Hiroshima, but in terms of explosive power it is inferior to the fall Tunguska meteorite(about 10 to 50 megatons) more than 10 times.
The fall of the Chelyabinsk meteorite immediately created a sensation both in time and place. In modern history, this space object is the first meteorite that fell into such a densely populated area, resulting in significant damage. So, during the explosion of a meteorite, the windows of more than 7 thousand houses were shattered, more than one and a half thousand people sought medical help, of which 112 were hospitalized.
In addition to significant damage, the fall of the meteorite also brought positive results. This event is the best documented to date. In addition, one video camera filmed the phase of falling into Chebarkul Lake of one of the large fragments of the asteroid.
Where did the Chelyabinsk meteorite come from?
For scientists, this question was not difficult. It emerged from the main asteroid belt of our solar system, a zone in the middle of the orbits of Jupiter and Mars, where the paths of most small bodies lie. The orbits of some of them, for example, asteroids of the Aten or Apollo group, are oblong and can pass through the orbit of the Earth.
Astronomers were able to accurately determine the flight path of the Chelyabinsk, thanks to a lot of photo and video recordings, as well as satellite photographs that captured the fall. Then the astronomers continued the path of the meteorite to reverse side, for the atmosphere, in order to build a complete orbit of this object.
Dimensions of fragments of the Chelyabinsk meteorite
Several groups of astronomers have tried to determine the path of the Chelyabinsk meteorite before it hit the Earth. According to their calculations, it can be seen that the semi-major axis of the orbit of the fallen meteorite was approximately 1.76 AU. (astronomical unit), this is the average radius of the earth's orbit; the point of the orbit closest to the Sun - perihelion, was at a distance of 0.74 AU, and the point most distant from the Sun - aphelion, or apohelion, at 2.6 AU.
These figures allowed scientists to try to find the Chelyabinsk meteorite in astronomical catalogs of already identified small space objects. It is clear that most of the previously established asteroids after some time “fall out of sight” again, and then some of the “lost” ones manage to “open” for the second time. Astronomers did not reject this option either, that the fallen meteorite, perhaps, is the “loss”.
Relatives of the Chelyabinsk meteorite
Although the search did not reveal a complete similarity, astronomers nevertheless found a number of probable "relatives" of the asteroid from Chelyabinsk. Scientists from Spain Raul and Carlos de la Fluente Marcos, having calculated all the variations in the orbits of the "Chelyabinsk", sought out its alleged forefather - the asteroid 2011 EO40. In their opinion, the Chelyabinsk meteorite broke away from him about 20-40 thousand years.
Another team (Astronomical Institute of the Czech Academy of Sciences), led by Jiri Borovichka, calculated the glide path of the Chelyabinsk meteorite and found that it is very similar to the orbit of asteroid 86039 (1999 NC43) with a size of 2.2 km. For example, the semi-major axis of the orbit of both objects is 1.72 and 1.75 AU, and the perihelion distance is 0.738 and 0.74.
Difficult life path
According to the fragments of the Chelyabinsk meteorite that fell to the surface of the earth, scientists "determined" its life history. It turns out that the Chelyabinsk meteorite is a peer of our solar system. When studying the proportions of isotopes of uranium and lead, it turned out that it is approximately 4.45 billion years old.
Fragment of the Chelyabinsk meteorite found on the lake Chebarkul
His difficult biography is indicated by dark threads in the thickness of the meteorite. They arose during the melting of substances that got inside as a result of a strong blow. This shows that approximately 290 million years ago, this asteroid withstood a powerful collision with some kind of cosmic object.
According to the scientists of the Institute of Geochemistry and Analytical Chemistry. Vernadsky RAN, the collision took about a few minutes. This is indicated by the streaks of iron nuclei, which did not have time to fully melt.
At the same time, scientists from the IGM SB RAS (Institute of Geology and Mineralogy) do not reject the fact that traces of melting may have appeared due to excessive convergence cosmic body with the sun.
meteor showers
Several times a year, meteor showers illuminate the clear night sky like stars. But they really have nothing to do with the stars. These small cosmic particles of meteorites are literally celestial debris.
Meteoroid, meteor or meteorite?
Whenever a meteoroid enters the Earth's atmosphere, it generates a burst of light called a meteor or "shooting star". High temperatures, caused by the friction between the meteor and the gas in the Earth's atmosphere, heats the meteorite to the point where it glows. This is the same glow that makes the meteor visible from the surface of the Earth.
Meteors usually glow for a very short period of time - they tend to burn up completely before hitting the Earth's surface. If the meteor does not break up as it passes through the Earth's atmosphere and falls to the surface, then it is known as a meteorite. Meteorites are believed to come from the Asteroid Belt, although some pieces of debris have been identified as belonging to the Moon and Mars.
What are meteor showers?
Sometimes meteors fall in huge showers known as meteor showers. Meteor showers occur when a comet approaches the Sun and leaves debris behind it in the form of breadcrumbs. When the orbit of the Earth and the comet intersect, a meteor shower falls on the Earth.
So the meteors that form a meteor shower travel on a parallel path and at the same speed, so for observers they come from the same point in the sky. This point is known as the "radiant". By convention, meteor showers, especially regular ones, are named after the constellation they come from.
Meteorite- this is a solid extraterrestrial substance that was preserved during the passage through the atmosphere and reached the surface of the Earth. Meteorites are the most primitive of the SS, which have not experienced further fractionation since their formation. This is based on the fact that the relative distribution refractory el. in meteorites corresponds to the solar distribution. Meteorites are classified into (according to the content of the metal phase): Stone(aeroliths): achondrites, chondrites, iron stone(siderolites), Iron(siderites). Iron meteorites - consist of kamacite - native Fe of cosmic origin with an admixture of nickel from 6 to 9%. Iron stone meteorites Small distribution group. They have coarse-grained structures with equal weight proportions of silicate and Fe phases. (Silicate minerals - Ol, Px; Fe phase - kamacite with Widmanstätten intergrowths). Stone meteorites - consist of silicates of Mg and Fe with an admixture of metals. Subdivided into Chondrite, achondrite and carbonaceous.Chondrites: spheroidal segregations of the first mm or less in size, composed of silicates, less often silicate glass. Embedded in a Fe-rich matrix. The groundmass of chondrites is a fine-grained mixture of Ol, Px (Ol-bronzite, Ol-hypersthene and Ol-pijonitic) with nickel Fe (Ni-4-7%), troilite (FeS) and plagioclase. Chondrites - crystallized. or glassy drops, cat. Image. when melting a pre-existing silicate material subjected to heating. Achondrites: Do not contain chondrules, have a lower content. nickel Fe and coarser structures. Their main minerals are Px and Pl, some types are enriched in Ol. Achondrites are similar in composition and structural features to terrestrial Gabbroids. The composition and structure speak of a magmatic origin. Sometimes there are bubbly structures like lavas. Carbonaceous chondrites (large amounts of carbonaceous matter) Characteristic feature of carbonaceous chondrites - the presence of a volatile component, which indicates primitiveness (the removal of volatile elements did not occur) and did not undergo fractionation. Type C1 contains a large number of chlorite(aqueous Mg, Fe aluminosilicates), as well as magnetite, water-soluble salt, nativeS, dolomite, olivine, graphite, organ. connections. Those. since their image-I they are noun. at T, not > 300 0 С. chondrite meteorites lack of 1/3 chem. Email compared to composition carbonaceous chondrites, cat. closest to the composition of protoplanetary matter. The most likely cause of the shortage of volatile email. - sequential condensation el. and their compounds in reverse order of their volatility.
5.Historical and modern models of accretion and differentiation of protoplanetary matter O.Yu. Schmidt in the 40s expressed the idea that the Earth and the planets of the CG were formed not from hot clots of solar gases, but through the accumulation of HB. bodies and particles - planetesimals that experienced melting later during accretion (heating due to collisions of large planetesimals, up to a few hundreds of kilometers in diameter). Those. early differentiation of the core and mantle and degassing. Ex. relates two points of view. accumulation mechanism and ideas about the form of the layered structure of the planets. Models homogeneous and heterogeneous accretion: HETEROGENEOUS ACCRETION 1. Short-term accretion. Early heterogeneous accretion models(Turekian, Vinogradov) assumed that Z. accumulated from the material as it condensed from the protoplanetary cloud. Early models include an early > T accumulation of the Fe-Ni alloy, which forms the proto-core of Z., changing from lower. T by accretion of its outer parts from silicates. Now it is believed that in the process of accretion there is a continuous change. in the accumulating material of the Fe/silicate ratio from the center to the periphery of the formed planet. As the earth accumulates, it heats up and melts Fe, which separates from the silicates and sinks into the core. After the cooling of the planet, about 20% of its mass is added with material enriched in volatiles along the periphery. In the proto-earth, there were no sharp boundaries between the core and the mantle, a cat. established as a result of gravitation. and chem. differentiation at the next stage of the evolution of the planet. In the early versions, differentiation occurred mainly during the formation of the ZK, and did not capture the Earth as a whole. HOMOGENEOUS ACCRETION 2. A longer accretion time of 108 years is assumed. During the accretion of the Earth and the planets of the Earth, the condensing bodies had wide variations in composition from carbonaceous chondrites enriched in volatiles to substances enriched in refractory components of the Allende type. Planets of forms. from this set of meteorites in-va and their difference and similarity was determined by relative. proportions in-va different composition. It also took place macroscopic homogeneity of protoplanets. The existence of a massive core indicates that the alloy originally introduced by Fe-Ni meteorites, uniformly distributed throughout the Earth, separated out in the course of its evolution into the central part. Homogeneous in composition the planet was stratified into shells in the process of gravitational differentiation and chemical processes. Modern model of heterogeneous accretion to explain the chem. the composition of the mantle is being developed by a group of German scientists (Wencke, Dreybus, Yagoutz). They found that the content in the mantle of moderately volatile (Na, K, Rb) and moderately siderophilic (Ni, Co) el., with different. The distribution coefficients of Me/silicate have the same abundance (normalized by C1) in the mantle, and the most strongly siderophile elements have excess concentrations. Those. the core was not in equilibrium with the mantle reservoir. They proposed heterogeneous accretion :1. Accretion begins with the accumulation of a strongly reduced component A, devoid of volatile elements. and containing all the other email. in quantities corresponding to C1, and Fe and all siderophiles in the reduced state. With an increase in T, the formation of a nucleus begins simultaneously with accretion. 2. After accretion, more and more oxidized material, component B, begins to accumulate in 2/3 of the earth's mass. and transfer them to the kernel. A source of moderately volatile, volatile and moderately siderophilic el. in the mantle yavl. component B, which explains their close relative abundance. Thus, the Earth is 85% composed of component A and 15% of component B. In general, the composition of the mantle is formed after separation of the core by homogenization and mixing of the silicate part of component A and the substance of component B.
6. isotopes chemical elements. isotopes - atoms of the same electron, but having a different number of neutrons N. They differ only in mass. isotons - atoms of different el., having different Z, but the same N. They are arranged in vertical rows. isobars - atoms of different el., in a cat. equal masses. numbers (A=A), but different Z and N. They are arranged in diagonal rows. Nuclear stability and isotope abundance; radionuclides The number of known nuclides is ~ 1700, of which ~ 260 are stable. On the nuclide diagram, stable isotopes (shaded squares) form a band surrounded by unstable nuclides. Only nuclides with a certain ratio of Z and N are stable. The ratio of N to Z increases from 1 to ~ 3 with increasing A. 1. Nuclides are stable, in a cat. N and Z are approximately equal. Up to Ca in N=Z nuclei. 2. Most stable nuclides have even Z and N. 3. Less common are stable nuclides with even numbers. Z and odd. N or even N and odd. Z. 4. Rare stable nuclides with odd Z and N.
number of stable nuclides | ||||
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In kernels from even. Z and N nucleons form an ordered structure, which determines their stability. The number of isotopes is less in light email. and took away. in the middle part of the PS, reaching a maximum for Sn (Z=50), which has 10 stable isotopes. Elements with odd. Z stable isotopes no more than 2.
7. Radioactivity and its types Radioactivity - spontaneous transformations of the nuclei of unstable atoms (radionuclides) into stable nuclei of other elements, accompanied by emission of particles and/or radiation of energy. St. glad-ty does not depend on the chemical. Holy atoms, but determined by the structure of their nuclei. Radioactive decay is accompanied by changes. Z and N of the parent atom and leads to the transformation of an atom of one el. into an atom of another email. It has also been shown by Rutherford and other scientists that he is glad. the decay is accompanied by the emission of radiation of three different types, a, b, g. a-rays - streams of high-speed particles - He nuclei, b - rays - streams e - , g - rays - electromagnetic waves with high energy and shorter λ. Types of radioactivity a-decay- decay by emission of a-particles, it is possible for nuclides with Z> 58 (Ce), and for a group of nuclides with small Z, including 5He, 5Li, 6Be. a-particle consists of 2 P and 2N, there is a shift of 2 positions in Z. The initial isotope is called parental or maternal, and the newly formed - child.
b-decay- has three types: normal b-decay, positron b-decay and e - capture. Ordinary b-decay- can be considered as the transformation of a neutron into a proton and e - , the last or beta particle - is ejected from the nucleus, accompanied by the emission of energy in the form of g-radiation. The daughter nuclide is an isobar of the parent, but its charge is greater.
There is a series of decays until a stable nuclide is formed. Example: 19 K40 -> 20 Ca40 b - v - Q. Positron b-decay- emission from the nucleus of a positive particle of a positron b, its formation - the transformation of a nuclear proton into a neutron, positron and neutrino. The daughter nuclide is an isobar but has a smaller charge.
Example, 9 F18 -> 8 O18 b v Q while the number N decreases. Atoms to the left of the region of nuclear stability are neutron-deficient, they undergo positron decay, and their number N increases. Thus, during b- and b-decay, there is a tendency for Z and N to change, leading to the approach of daughter nuclides to the zone of nuclear stability. e – capture- capture of one of the orbital electrons. High probability of capture from the K-shell, cat. closest to the core. e - capture causes emission from the neutrino nucleus. Daughter nuclide yavl. isobar, and occupies the same position relative to the parent as in positron decay. b - radiation is absent, and when a vacancy is filled in the K-shell, X-rays are emitted. At g radiation neither Z nor A change; when the nucleus returns to its normal state, energy is released in the form g-radiation. Some daughter nuclides of the natural isotopes U and Th can decay either by emitting b-particles or by a-decay. If b-decay occurred first, then a-decay followed, and vice versa. In other words, these two alternative decay modes form closed cycles and always lead to the same end product - stable isotopes of Pb.
8. Geochemical consequences of the radioactivity of terrestrial matter. Lord Kelvin (William Thomson) from 1862 to 1899 performed a series of calculations, cat. imposed restrictions on the possible age of the Earth. They were based on consideration of the luminosity of the Sun, the influence of lunar tides, and the processes of cooling of the Earth. He came to the conclusion that the age of the Earth is 20-40 million years. Later, Rutherford performed the determination of the age of U min. and received values of about 500 million years. Later, Arthur Holmes in his book "The Age of the Earth" (1913) showed the importance of the study of radioactivity in geochronology and gave the first GHS. It was based on consideration of data on the thickness of sedimentary deposits and on the content of radiogenic decay products - He and Pb in U-bearing minerals. Geological scale- the scale of the natural historical development of the ZK, expressed in numerical units of time. The accretion age of Earth is about 4.55 billion years. The period up to 4 or 3.8 billion years is the time of differentiation of the planetary interior and the formation of the primary crust, it is called katarchey. The longest period of life of Z. and ZK is the Precambrian, cat. extends from 4 billion years to 570 million years, i.e. about 3.5 billion years. The age of the most ancient rocks known now exceeds 4 billion years.
9. Geochemical classification of elements by V.M. HolshmidtBased on: 1- distribution email. between different phases of meteorites - separation during the primary HX differentiation of Z. 2 - specific chemical affinity with certain elements (O, S, Fe), 3 - structure of electron shells. The leading elements that make up meteorites are O, Fe, Mg, Si, S. Meteorites consist of three main phases: 1) metal, 2) sulfide, 3) silicate. All e-mail are distributed between these three phases in accordance with their relative affinity for O, Fe and S. In the Goldschmidt classification, the following groups of elec. are distinguished: 1) siderophilic(loving iron) - metal. phase of meteorites: el., forming alloys of arbitrary composition with Fe - Fe, Co, Ni, all platinoids (Ru, Rh, Pd, Pt, Re, Os, Ir), and Mo. They often have a native state. These are transitional elements of group VIII and some of their neighbors. Form the inner core Z. 2) Chalcophilic(copper-loving) - the sulfide phase of meteorites: elements that form natural compounds with S and its analogues Se and Te also have an affinity for As (arsenic), sometimes they are called (sulfurophilic). Easily pass into a native state. These are elements of secondary subgroups I-II and main subgroups III-VI groups of PS from 4 to 6 period S. The most famous are Cu, Zn, Pb, Hg, Sn, Bi, Au, Ag. Siderophile el. – Ni, Co, Mo can also be chalcophilic with a large amount of S. Fe under reducing conditions has an affinity for S (FeS2). In the modern model of the star, these metals form the outer, sulfur-enriched core of the star.
3) lithophilic(loving stone) - silicate phase of meteorites: el., having an affinity for O 2 (oxyphilic). They form oxygen compounds - oxides, hydroxides, salts of oxygen acids-silicates. In compounds with oxygen, they have an 8-electron ext. shell. This is the largest group of 54 elements (C, common petrogenic - Si, Al, Mg, Ca, Na, K, elements of the iron family - Ti, V, Cr, Mn, rare - Li, Be, B, Rb, Cs, Sr , Ba, Zr, Nb, Ta, REE, i.e. all the rest except atmophilic ones). Under oxidizing conditions, iron is oxyphilic - Fe2O3. form the mantle Z. 4) Atmophilic(har-but gaseous state) - chondrite matrix: H, N inert gases (He, Ne, Ar, Kr, Xe, Rn). They form the atmosphere Z. There are also such groups: rare earth Y, alkaline, large-ion lithophile elements LILE (K, Rb, Cs, Ba, Sr), highly charged elements or elements with high field strength HFSE (Ti, Zr, Hf, Nb, Ta , Th). Some definitions of email: petrogenic (rock-forming, main) minor, rare, trace elements- with conc. no more than 0.01%. scattered- microel. not forming their own minerals accessory- form accessory min. ore- form ore mines.
10. The main properties of atoms and ions that determine their behavior in natural systems. Orbital radii - radii of the maxima of the radial density e – ext. orbitals. They reflect the sizes of atoms or ions in the free state, i.e. outside the chem. connections. The main factor is e - the structure of the electron, and the more e - shells, the larger the size. For def. sizes of atoms or ions in an important way yavl. Def. distance from the center of one atom to the center of another, cat. is called the bond length. For this, X-ray methods are used. In the first approximation, atoms are considered as spheres, and the “principle of additivity” is applied, i.e. it is believed that the interatomic distance is the sum of the radii of the atoms or ions that make up the in-in. Then knowing or accepting a certain value as the radius of one el. you can calculate the dimensions of all others. The radius calculated in this way is called effective radius . coordination number is the number of atoms or ions located in close proximity around the considered atom or ion. CF is determined by the ratio R k /R a: Valence - the amount of e - given or attached to the atom during the formation of chemical. connections. Ionization potential is the energy required to remove e- from an atom. It depends on the structure of the atom and is determined experimentally. The ionization potential corresponds to the voltage of the cathode rays, which is sufficient to ionize an atom of this email. There may be several ionization potentials, for several e - removed from the external. e - shells. The separation of each subsequent e - requires more energy and may not always be. Usually use the ionization potential of the 1st e - , cat. detects periodicity. On the curve of ionization potentials, alkali metals, which easily lose e - , occupy minima on the curve, inert gases - peaks. As the atomic number increases, the ionization potentials increase in the period and decrease in the group. The reciprocal is the affinity ke – . Electronegativity - the ability to attract e - when entering into compounds. The halogens are the most electronegative, the alkali metals the least. Electronegativity depends on the charge of the nucleus of an atom, its valency in a given compound, and the structure of the e-shells. Repeated attempts have been made to express EC in units of energy or in conventional units. The EC values regularly change by groups and periods of PS. EO is minimal for alkali metals and increases for halogens. In lithophilic cations, EO is reduced. from Li to Cs and from Mg to Ba, i.e. with a zoom ionic radius. In chalcophile el. EO is higher than that of lithophiles from the same PS group. For anions of the O and F groups, the EO decreases down the group and, therefore, it is maximum for these el. Email with a sharp different meanings EOs form compounds with an ionic type of bond, and with close and high - with a covalent type, with close and low - with a metallic type of bond. The ionic potential of Cartledge (I) is equal to the ratio of valency to R i , it reflects the properties of cationicity or ionogenicity. V.M. Golshmidt showed that the properties of cationicity and anionicity depend on the ratio of valence (W) and R i for ions of the noble gas type. In 1928, K. Cartledge called this ratio the ionic potential I. At small values of I el. behaves like a typical metal and cation (alkali and alkaline earth metals), and at large - like a typical non-metal and anion (halogens). These relationships are conveniently depicted graphically. Diagram: ionic radius - valency. The value of the ionic potential allows us to judge the mobility of email. V aquatic environment. Email with low and high values of I are the most mobile easily (with low values they pass into ionic solutions and migrate, with high values they form complex soluble ions and migrate), and with intermediate ones they are inert. The main types of chem. bonds, character bonds in the main groups of minerals. Ionic- image due to the attraction of ions with opposite charges. (with a large difference in electronegativity) Ionic bonding predominates in most mines. ZK - oxides and silicates, this is the most common type of bond also in hydro and atmospheres. Communication provides easy dissociation of ions in melts, solutions, gases, due to which there is a wide migration of chemical. El., their dispersion and end in the terrestrial geospheres. covalent - noun. due to the interaction e - used by different atoms. Typical for e. with an equal degree of attraction e – , i.e. EO. Har-na for liquid and gaseous substances (H2O, H2, O2, N2) and less for a crystal. Sulfides, related compounds As, Sb, Te, as well as monoel are characterized by a covalent bond. non-metal compounds - graphite, diamond. Covalent compounds are characterized by low solubility. metal- a special case covalent bond, when each atom shares its e - with all neighboring atoms. e - capable of free movement. Typical for native metals (Cu, Fe, Ag, Au, Pt). Many min. have a connection, a cat. partly ionic, partly covalent. in sulfide mines. the covalent bond is maximally manifested, it takes place between the metal and S atoms, and the metallic one - between the metal atoms (metal, brilliance of sulfides). Polarization - this is the effect of distortion of the e-cloud of an anion by a small cation with a large valence, so that a small cation, attracting a large anion to itself, reduces its effective R, itself entering its e-cloud. So the cation and anion are not regular spheres, and the cation causes the deformation of the anion. The higher the charge of the cation and the smaller its size, the stronger the effect of polarization. And the larger the size of the anion and its negative charge, the stronger it is polarized - deformed. Lithophilic cations (with 8 electron shells) cause less polarization than ions with completed shells (like Fe). Chalcophile ions with large serial numbers and high-valent cause the strongest polarization. This is associated with the formation of complex compounds: 2-, , 2-, 2-, cat. soluble and yavl. the main carriers of metals in hydrothermal solutions.
11.Status (form of location) email. in nature. In GC allocate: actually min. (crystal. phases), impurities in min., various forms of the scattered state; email location form in nature carries information about the degree of ionization, har-re chem. email connections in phases, etc. V-in (el.) is in three main forms. The first is the end atoms, the image. stars are different. types, gaseous nebulae, planets, comets, meteorites and space. tv. particles in-va. Degree of conc. V-va in all bodies is different. The most scattered states of atoms in gaseous nebulae are held by gravitational forces or are on the verge of overcoming them. The second - scattered atoms and molecules, an image of interstellar and intergalactic gas, consisting of free atoms, ions, molecules, e -. Its quantity in our Galaxy is much less than that which is concentrated in stars and gaseous nebulae. Interstellar gas is located at different sparse stages. The third - intensively migrating, flying with tremendous speed atomic nuclei and elementary particles that make up cosmic rays. IN AND. Vernadsky singled out the main four forms of finding chem. Email in the ZK and on its surface: 1. rocks and minerals (solid crystalline phases), 2. magmas, 3. scattered state, 4. living matter. Each of these forms is distinguished by the special state of their atoms. Ex. and other allocation of forms of finding e-mail. in nature, depending on the specific sv-in themselves email. A.I. Perelman singled out mobile and inert forms finding chem. Email in the lithosphere. By his definition, movable form is such a state of chemistry. Email in gp, soils and ores, being in a cat. Email can easily pass into the solution and migrate. inert form represents such a state in urban settlements, ores, weathering crust and soils, in the cat. Email under the conditions of this situation, it has a low migratory mode and cannot move into the solution and migrate.
12. Internal factors of migration.
Migration- movement of chemicals Email in geospheres Z, leading to their dispersion or conc. Clarke - medium conc. in the main types of GP ZK of each chem. Email can be considered as a state of its equilibrium under the conditions of a given chemical. Wednesdays, a deviation from a cat. gradually reduced by migrating this email. Under terrestrial conditions, the migration of chemical Email happens in any medium - TV. and gaseous (diffusion), but easier in a liquid medium (in melts and aqueous solutions). At the same time, the forms of migration of chemical Email are also different - they can migrate in atomic (gases, melts), ionic (solutions, melts), molecular (gases, solutions, melts), colloidal (solutions) forms and, in the form of detrital particles (air and water environment ). A.I. Perelman distinguishes four types of chemical migration. El.: 1.mechanical, 2.phys.-chemical, 3.biogenic, 4.technogenic. The most important internal factors: 1. Thermal properties of electricity, i.e. their volatility or infusibility. El., having a condensation T of more than 1400 o K are called refractory platinoids, lithophilic - Ca, Al, Ti, Ree, Zr, Ba, Sr, U, Th), from 1400 to 670 o K - moderately volatile. [lithophile - Mg, Si (moderately refractory), many chalcophile, siderophile - Fe, Ni, Co],< 670 o K – летучими (атмофильные). На основании этих св-в произошло разделение эл. по геосферам З. При магм. процессе в условиях высоких Т способность к миграции будет зависеть от возможности образования тугооплавких соединений и, нахождения в твердой фазе. 2. Хим. Св-ва эл. и их соединений. Атомы и ионы, обладающие слишком большими или слишком малыми R или q, обладают и повышенной способностью к миграции и перераспределению. Хим. Св-ва эл. и их соединений приобретают все большее значение по мере снижения T при миграции в водной среде. Для литофильных эл. с низким ионным потенциалом (Na, Ca, Mg) в р-рах хар-ны ионные соединения, обладающие высокой раствор-ю и высокими миграционными способностями. Эл. с высокими ионными потенциалами образуют растворимые комплексные анионы (С, S, N, B). При низких Т высокие миграционные способности газов обеспечиваются слабыми molecular bonds their molecules. Glad. Saint-va, determine the change in the isotopic composition and the appearance of nuclei of other el.
What are the chemical composition of meteorites? and got the best answer
Answer from Tata[guru]
Chemical composition.
The chemical composition of asteroids is similar to the chemical composition of meteorites, so the description of the composition of meteorites is fully applicable to asteroids. Comets, on the other hand, have a more complex composition, as they consist of several parts (core, head and tail) consisting of various chemical elements.
We can judge the chemical composition of meteorites by the composition of those meteorites that fell into the hands of scientists. To date, they are usually divided into three classes: stone, stone-metal and metal. Asteroids are much larger in size than meteorites, and so far their structure can only be assumed from their reflectivity. There are three groups of asteroids - dark, light and metallic.
The table below gives only average values for the content of individual chemical elements in meteorites of different classes. It follows from the above that there are only three classes of meteorites and asteroids, but this is not entirely true. The classes of meteorites are divided into big number subclasses, that is, the chemical composition of meteorites within each class varies widely.
Consider metallic meteorites. The main chemical elements, the content of which determines the type of meteorite, are iron and nickel. Therefore, depending on the nickel content, meteorites are subdivided into hexahedrites, octahedrites and ataxites. But even within these subclasses, meteorites differ in nickel content. Ataxites, depending on the nickel content, are divided into rich and poor in nickel.
The average chemical composition of nickel iron, which forms inclusions in stony meteorites and mesosiderites, and also forms the basis of pallastites, is, in general, close to the average composition of fine and very fine structure octahedrites.
The distribution of chemical elements in meteorites obeys the same pattern as on Earth, that is, the Oddo-Harkins law. According to this law, an element with an even ordinal number is more common than its neighboring elements with odd ordinal numbers.
It was also installed interesting feature content of rare impurities in meteorites. It turned out that the amount of these impurities contained in meteorites in millionths of a percent depends on the chemical composition of the meteorite, in particular, on the nickel content. Thus, the maximum content of gallium is observed in hexahedrites, nickel-poor ataxites and octahedrites, and the minimum content is observed in nickel-poor ataxites. In other words, the higher the nickel content in a meteorite, the less gallium it contains.
In meteorites, as constituent parts contains a number of gases. Hydrogen, nitrogen, carbon monoxide and carbon dioxide. It was also found that hydrogen and carbon monoxide predominate in metallic meteorites, while carbon dioxide predominates in stone meteorites. Also in meteorites there are some radioactive elements, in particular: uranium, helium, potassium, thorium. This allows, by measuring the amount of radioactive elements and their decay products, to determine the age of meteorites. (Age here refers to the period of time that has elapsed since the moment of solidification of the substance that makes up meteorites.
metal meteorites.
Hexahedrites are entirely composed of one mineral type of iron - kamacite. Accessory minerals are represented by troilite and schreibersite; Dobreelite occurs as an occasional mineral.
Octahedrites are composed of both mineral types of nickel iron, that is, kamacite (ground mass) and taenite. The largest amount of taenite is contained in very fine-structured octahedrites, while in coarse-grained octahedrites, the content of taenite is very small. Very rare are octahedrites, such as Sikhote-Alin, almost entirely composed of kamacite.
ATAXITES consist entirely of a mixture of grains of kamacite and taenite, called plessite. Thus, in their mineral composition, ataxites are similar to octahedrites, differing from