How are diamonds formed in nature?

Diamond has long been the benchmark for strength, indestructibility and stability. However, it is helpful to know how diamonds are formed.

Not so few people held jewelry with diamonds at least once in their life. But the situation is much worse about the origin of the reference gem. Even experienced mineralogists and geologists cannot say with complete confidence which version is true.

Diamonds became known long before our era. Passing a stone with such unusual properties was impossible.

One of the old legends says that:

• diamond crystals are living things;
• they may belong to different sexes;
• these organisms "absorb celestial dew";
• they can grow in size and even multiply.

Ancient Indian mythology asserted that a diamond appears in nature when five basic natural principles come together. These include:

• air;
• water;
• land;
• sky;
• energy.

In the ancient manuscripts, they immediately began to note that the diamond is very hard and distinguished by an extraordinary brilliance. It was often written that this mineral can appear "on a rock, in the sea and on the hills above the gold mines."

The legends of Sinbad the Sailor say that somewhere there is a rather deep gorge, at the bottom of which the primary deposits of diamonds are hidden. But, of course, all this very weakly correlated with reality.

We must pay tribute to the people of antiquity and the Middle Ages. Finding the real cause of diamond formation shows that human thought has never stood still. Nevertheless, the first serious versions of his appearance could be advanced only after 1797 - it was then that the chemical composition of the mineral was precisely determined.

A little later, it was found that the difference between diamond, graphite and various coal options is due to the arrangement of atoms inside the crystal lattices.

The essence of the concept - the occurrence of these minerals as a result of the movement of magma. It is assumed that most of them appeared not earlier than 2.5 billion and no later than 100 million years ago. It happened at a depth of about 200 km. There, graphite was simultaneously affected by a high temperature of about 1 thousand degrees and a pressure of 50 thousand atmospheres.

One version of the version implies that semi-precious stones were already formed on the surface of the earth.

This occurred as a result of solidification of lava in contact with air. The problem is that the temperature and pressure in such a situation is not too high. For this reason, this concept is not popular among professionals.

There is an alternative assumption that gems are formed from ultrabasic rocks.

Only later, when the magma went up, was a stone thrown with it. The overwhelming majority of geologists are inclined to this approach. The intermediate version is that diamonds form when the magma has already started moving upward, but has not yet reached the vent.

Such changes in the structure significantly strengthen the stone itself and give it the qualities so valued in the commodity market.

The former diamond reserves associated with old deposits and kimberlite pipes are becoming less common. And the need for stones is great.Sometimes, residents of volcanic areas some time after eruptions extract the hardest mineral from hardened lava. But the conditions required for its appearance are obtained not only due to volcanic processes, while some diamond researchers pay attention not only to the depths of the Earth, but also upwards.

Repeatedly already in the inspection of pieces of meteorites, whole diamonds (or their individual particles) were found. The quality of such minerals was excellent.

Once, when a meteorite fell in the United States, precious stones were found in the walls of the crater. But they were somewhat different from the usual options. The difference, according to some information, concerns the structure of the crystal lattice - it does not affect the external appearance.

Some experts believe that diamonds are already inside the meteorites. When they are destroyed, the stones are “free”.

More popular is the idea that a stone appears already when it hits an earth’s surface. This process provokes the release of considerable mechanical and thermal energy.

For this reason, both the temperature and the pressure in the center (where the crater remains) sharply increases. These factors lead to the characteristic transformation of carbon.

Spectrographic observations have shown that gaseous carbon (in pure form or in conjunction with nitrogen, hydrogen) is present in the solar atmosphere. Astronomers and cosmologists believe that this element was also in colossal clots of gas, dust, which became the forerunners of all the planets. When cooled, gases liquefy. Gradually, liquid substances were distributed by weight: the heavier ones sank down, and the light ones floated upward.

Liquid magmatic masses in the initial period of the Earth’s development easily broke through a thin layer of the earth's crust. Carbon actively reacted with hydrogen. As a result, the crust gradually lost this chemical element.

At the present stage of the geological history of our planet, it accounts for about 1%. Such an excursion makes it possible to draw a seemingly paradoxical conclusion: there are no deep contradictions between volcanic and cosmic hypotheses.

The only difference is in the ways in which she came to a particular place. Experts believe that most of the carbon is now in the outer part of the mantle, because there the high temperature and pressure lead to the formation of compounds of the main substance with heavy metals. But some carbon atoms are attached to each other.

Still famous Vernadsky and Fersman put forward the assumption that diamonds are born just like that. Two scientists belong to the scheme of geochemical transformations of carbon. According to this classical scheme, both diamond and graphite are concentrated mainly in the lower layers of the lithosphere.

The deepest wells on Earth only reach a depth of 10-12 km. In this case, the birth of diamonds, even according to Fersman, occurs at depths of at least 30–40 km. That is the average crustal thickness. Check the mantle version at the current level of drilling, especially will not work. Returning to the mantle-magmatic version, it is worth pointing out that according to it, carbon can turn into diamonds if:

• for hundreds of million years there will be a chemically uniform environment;
• at the same time weak thermal gradients will be maintained;
• the pressure will consistently exceed 5 thousand Pa.

The corresponding parameters, based on the ideas of modern geology, are achieved at a depth of 100 to 200 km.

Another prerequisite for "success" is the presence of a diatreme or breakthroughs of the earth's crust. On continental platforms, magmatic melt, saturated with appreciable amounts of gases, can penetrate it. As a result, kimberlite pipes known to all are formed.

There is also an alternative fluid version, according to which the strongest mineral crystallizes at a lesser depth. The starting point is the decomposition of methane or its incomplete oxidation. An oxidizing agent is a mixture of hydrogen, carbon, oxygen and sulfur. Four elements can exist both in the liquid and in the gaseous aggregate state.

From the fluid hypothesis it follows that Diamonds can appear at temperatures from 1 thousand degrees, acting simultaneously with pressure from 100 to 500 pascals.

In other places, large-scale mining is not feasible. Over time, geological processes lead to the destruction of the upper part of the primary deposits. Diamonds are carried away from there (and carried away in the past) with flowing water. When the mineral is deposited again, placers appear.

How diamonds are mined, see the next video.