What is meteoric iron? How does it appear on Earth? You will find answers to these and other questions in the article. Meteoritic iron is a metal found in meteorites and consisting of several mineral phases: taenite and kamacite. It makes up the majority of metallic meteorites, but is also found in other types. Consider meteoric iron below.
Structure
When a polished cut is etched, the structure of meteorite iron appears in the form of the so-called Widmanstätten figures: intersecting beams-strips (kamacite) bordered by shiny narrow ribbons (taenite). Sometimes you can see polygonal fields-platforms.
Fine-grained mixture of taenite and kamacite forms plessite. The iron we are considering in meteorites of the hexahedrite type, which is almost entirely composed of kamacite, forms a structure in the form of parallel thin lines, called non-man.
Application
In ancient times, people did not know how to make metal from ore, soits only source was meteoric iron. It has been proven that elementary tools from this substance (identical in shape to stone ones) were created as early as the Bronze Age and the Neolithic. A dagger found in the tomb of Tutankhamun and a knife from the Sumerian town of Ur (about 3100 BC) were made from it, beads found 70 km from Cairo, in places of eternal rest, in 1911 (about 3000 BC). BC).
Tibetan sculpture was also created from this substance. It is known that King Numa Pompilius (Ancient Rome) had a metal shield made from "a stone that fell from the sky." In 1621, a dagger, two sabers and a spearhead were forged from heavenly iron for Jahangir (the ruler of an Indian principality).
A saber made of this metal was presented to Tsar Alexander I. According to legend, Tamerlane's swords also had a cosmic origin. Today, heavenly iron is used in jewelry production, but most of it is used for scientific experiments.
Meteorites
Meteorites are 90% metal. Therefore, the first person began to use heavenly iron. How to distinguish it from the earth? This is very easy to do, because it contains about 7-8% nickel impurities. It is not for nothing that in Egypt it was called stellar metal, and in Greece - heavenly. This substance was considered very rare and expensive. It's hard to believe, but she was previously framed in gold frames.
Star iron is not resistant to corrosion, soproducts made from it are rare: they simply could not survive to this day, as they crumbled from rust.
According to the method of detection, iron meteorites are divided into falls and finds. Falls are called such meteorites, the decline of which was visible and which people were able to find shortly after they landed.
Findings are meteorites found on the surface of the Earth, but no one observed their fall.
Meteorites falling
How does a meteorite fall to Earth? Today, more than a thousand falls of heavenly wanderers have been recorded. This list includes only meteors whose passage through the Earth's atmosphere was recorded by automatic equipment or observers.
Star rocks enter our planet's atmosphere at about 11-25 km/s. At this speed, they begin to warm up and glow. Due to ablation (charring and blowing off by a counter flow of particles of the substance of a meteorite), the weight of a body that has reached the Earth's surface can be less, and sometimes significantly less than its mass at the entrance to the atmosphere.
The fall of a meteorite to Earth is an amazing phenomenon. If the meteorite body is small, then at a speed of 25 km / s it will burn without residue. As a rule, out of tens and hundreds of tons of primary mass, only a couple of kilograms and even grams of substance reach the earth. Traces of combustion of celestial bodies in the atmosphere can be found throughout almost the entire trajectory of their fall.
The fall of the Tunguska meteorite
This mysterious event happened in 1908, June 30th. How did the fall of the Tunguska meteorite occur? The celestial body fell in the area of the Tunguska Podkamennaya River at 07:15 local time. It was early morning, but the villagers had long since woken up. They were engaged in current affairs, which in the village courtyards require unceasing attention from the very sunrise.
The Podkamennaya Tunguska itself is a full-flowing and mighty river. It flows on the lands of the present Krasnoyarsk Territory, and originates in the Irkutsk region. It makes its way through the taiga wilderness areas, replete with wooded high banks. This is a godforsaken region, but it is rich in minerals, fish and, of course, impressive hordes of mosquitoes.
The mysterious event started at 6:30 local time. Residents of villages located along the banks of the Yenisei saw a fireball of impressive size in the sky. It moved from south to north, and then disappeared over the taiga. At 07:15 a bright flash lit up the sky. After a while there was a terrible roar. The earth shook, glass flew out of the windows in the houses, the clouds turned red. They kept this color for a couple of days.
Observatories located in different parts of the world recorded a blast wave of great strength. Next, people wanted to know what happened and where. It is clear that in the taiga, but it is very large.
It was not possible to organize a scientific expedition, because there were no rich patrons willing to pay for such research. Therefore, scientists first decided only to interview eyewitnesses. They talked with the Evenks andRussian hunters. They said that at first a strong wind blew and a loud whistle was heard. Further, the sky was filled with red light. After a thunderclap was heard, trees began to light up and fall. It got very hot. After a couple of seconds, the sky shone even more strongly, and the thunder rang out again. A second sun appeared in the sky, which was much brighter than the usual star.
Everything was limited to these indications. Scientists decided that a meteorite fell in the Siberian taiga. And since he landed in the area of Podkamennaya Tunguska, they called him Tunguska.
The first expedition was equipped only in 1921. Its initiators were academicians Fersman Alexander Evgenievich (1883-1945) and Vernadsky Vladimir Ivanovich (1863-1945). This journey was led by Kulik Leonid Alekseevich (1883-1942), the leading specialist of the USSR on meteorites. Then several more scientific campaigns were organized in 1927-1939. As a result of these studies, the assumptions of scientists were confirmed. In the basin of the Tunguska Podkamennaya River, a meteorite fell indeed. But the huge crater that the fallen body was supposed to create was not discovered. They did not find any crater at all, even the smallest one. But they found the epicenter of a powerful explosion.
It was installed on the trees. They stood there as if nothing had happened. And around them, in a radius of 200 km, there was a fallen forest. The surveyors decided that the explosion happened at an altitude of 5-15 km above the ground. In the 60s, it was established that the force of the explosion was equal to the power of a hydrogen bomb with a capacity of 50 megatons.
Today about the fall of this celestial bodyThere are a huge number of assumptions and theories. The official verdict says that it was not a meteorite that fell to Earth, but a comet - a block of ice interspersed with tiny solid cosmic particles.
Some researchers believe that an alien spaceship crashed over our planet. In general, almost nothing is known about the Tunguska meteorite. No one can name the parameters and mass of this stellar body. The prospectors will probably never come to the only correct concept. After all, how many people, so many opinions. Therefore, the mystery of the Tungus guest will give birth to more and more new hypotheses.
