Diamond deposits are characterized by limited distribution in the bowels of the earth. They are represented by the so-called placer and primary deposits. Placers are loose or cemented clastic deposits containing diamonds.
Diamond placers were formed in different geological eras. The most ancient of them date back to the Proterozoic time (about 2 billion years ago). Placers of this age are known in South Africa (in conglomerates of the Witwatersrand system), in Ghana (Birima), and in Brazil (Bahia, Minas Gerais). Placers of Cambrian-Silurian age (570-420 million years) are known in India. In the Urals, diamonds were found in Ordovician (450-420 million years old) gravelites, in Brazil and Bolivia - in Carboniferous (320 million years old) glacial deposits. In Yakutia, individual finds of diamonds are known in Permian (270 million years) and Jurassic (185 million years) deposits. In Brazil, Cretaceous deposits are known (140-100 million years), in Australia - Tertiary (70-10 million years). The most widespread, and the main ones in terms of industrial importance, are placers of Quaternary age (up to 1 million years). They are being intensively developed in Russia, Congo, Ghana, South Africa and others.
Geological structure of diamond deposits
According to their origin, diamond placers are divided into eluvial, deluvial, alluvial, coastal-marine and aeolian.
- Eluvial placers lie at the site of formation, that is, directly on the upper parts of the bedrock deposit, and are a product of its destruction.
- Colluvial placers occur on slopes. The material, which includes diamonds, has been somewhat displaced from primary sources, resulting in a weak roundness.
- Alluvial placers are formed in river valleys by the transport and deposition of clastic material (pebbles, gravel, sand) and diamonds contained in it by water flows. Depending on the location of placers to certain elements of a river valley, alluvial placers are divided into channel, spit, floodplain (valley), and terrace. Channel placers of diamonds are located directly in the river bed. They are constantly being washed away, being under the influence of water flow and moving downstream. There are areas in river beds where, due to peculiar conditions, light material is carried away, but heavy minerals and diamonds remain in place. Within these areas, enriched placers are formed. Spit placers are placers occurring on pebble spits, islands and shallows. Diamonds they are distributed very unevenly. The main part of diamonds is concentrated in the head and middle parts. Valley placers are placers confined to a floodplain or first terrace, where diamond-bearing layers of sediments occur in the form of strips that do not depend on the direction of the modern watercourse. The placers are at a stage of relative rest; they are rarely eroded, since they are usually covered by rock that does not contain diamonds (loams, sands, clays). Terrace placers are placers confined to terraces, i.e., areas on the slopes of a valley, rising at a height of several to 70 m or more above the modern riverbed. The latter are the remains of ancient riverbeds.
- Proluvial (spoon) placers occur in the valleys of ravines and small rivers and are formed due to the movement of detrital diamond-bearing material during floods or in watercourses after heavy rains. Diamonds in placers of this type are distributed unevenly due to the short-term action of water flows.
- Coastal-marine placers occur along coasts and are confined either to coastlines (modern and ancient) or to the coastal shelf zone. Their formation is associated with the transport of diamonds by rivers to the coastal zones of the sea basin or with the erosion of older diamond-bearing deposits by waves. There are coastal (beach) placers, confined to coastal ramparts and the beach, and terraced ones, associated with sea terraces.
- Aeolian placers are created as a result of the processing of other types of placers by the wind. They have no practical significance.
Placers of mixed origin are known.
Primary diamond deposits
Studying diamond placers led to the discovery of their original sources. As indicated, the first primary deposit was found in South Africa in 1870 near the village of Kimberley, from where the rocks hosting diamonds were called kimberlites, and the geological bodies they formed, depending on their shape, were called kimberlite pipes, kimberlite dikes and kimberlite veins.
- Kimberlite pipes are cylindrical bodies, the diameter of which ranges from 25 to 800 m. The latter usually decreases with depth. There is no exact data on the depth of the tubes. One can only assume that it is at least 2-5 km.
- Kimberlite dykes are bodies bounded by parallel walls. They were formed as a result of the filling of vertical or inclined cracks in the earth's crust with kimberlite rock. In addition, at depth, some of the kimberlite pipes transform into dikes, which has been established in several cases by mining. The thickness of kimberlite dikes is small - from 0.2 to 6-10 and less often more than 10 m.
- Kimberlite veins are irregularly shaped bodies that were formed as a result of kimberlite cracks of various shapes and sizes, with a thickness of 1-2 m.
Kimberlite- This is an igneous rock, poor in silicic acid and with slightly increased alkalinity. It consists mainly of serpentine, olivine and mica. In addition, diamond, garnet (pyrope), ilmenite, chrome diopside and other minerals are found in kimberlites. True, these minerals are not necessarily present in all kimberlite bodies. For example, diamond-bearing pipes are mainly kimberlite pipes. The veins and dikes contain almost no diamonds. In addition to the listed minerals, kimberlites contain fragments of various rocks - both those occurring at depth and rocks among which kimberlite bodies occur. The content of the latter sometimes reaches 60-70%.
There is still no consensus on the origin of kimberlite magma. Most researchers are of the opinion that kimberlite magma has a deep origin, that is, it was formed at a depth of approximately 60-100 km from the surface, and this magma penetrated into the upper layers in places where kimberlite rocks are distributed along tectonic cracks.
To date, more than 600 kimberlite bodies have been found around the globe. Their study made it possible to outline some patterns in their placement. Firstly, the main primary diamond deposits are confined to ancient platforms, i.e., to areas of the earth's crust that are characterized by a two-tiered structure. The lower tier consists of crystalline rocks crumpled into folds, the upper one - of horizontally lying sedimentary and volcanic rocks, the thickness of which reaches 3-5 km.
It is in such areas that the primary diamond deposits of Yakutia, South Africa, and India are located.
Secondly, within the platforms, the primary diamond deposits are mainly kimberlite pipes and, in some cases, kimberlite dikes. Of the more than 600 kimberlite bodies, less than half are diamond-bearing, with increased concentrations of diamonds noted in only 6-10% of the bodies.
A detailed study of kimberlite bodies shows that their formation did not occur in one stage and was multi-stage.
The sequence of formation of kimberlite bodies appears to us as follows:
- some kimberlite minerals (olivine, pyrope, ilmenite, apparently partly diamonds) were formed at great depths;
- the formation of individual kimberlite pipes could not occur immediately from the first magma chamber, but in stages, and such magma chambers repeatedly moved upward;
- Next comes the intrusive stage of direct introduction of kimberlite magma into the upper floors. At this time, kimberlite dike veins and some pipes are formed;
- in the upper platform sedimentary strata, the intrusive stage is followed by an explosive (explosive volcanic) stage. The latter is distinguished by the short duration of its active activity. Along with the breakthrough of the host rocks, some of which are subject to crushing, the kimberlites formed at the first stage are also subject to crushing, followed by cementation with subsequent portions of kimberlite material. In this way, kimberlite breccia is formed, and explosions could be repeated.
The formation of another part of the diamonds found in kimberlites should be associated with this period. There are various hypotheses regarding the conditions under which diamonds are formed in bedrock deposits. One of the most common is that diamonds crystallize from magma at great depths. This hypothesis was developed by A. S. Fersman, V. S. Sobolev, Williams, A. du Toit and other scientists. Recently, researchers V.G. Vasiliev, V.V. Kovalsky, N.V. Chersky, when studying the diamond deposits of Yakutia and the results of obtaining artificial diamonds, have expressed a different point of view, arguing that diamonds were formed in special centers located in the thickness of sedimentary rocks platform cover (upper tier of the platform) or in the boundary zone of the upper (sedimentary) and lower (folded crystalline basement) tiers of the platform. The thermodynamic conditions necessary for this (high temperature and pressure) were provided due to explosive processes resulting from the accumulation in the source of a mixture of explosive gases coming from the host rocks. And since carbon is necessary for the formation of diamond, it is assumed that it was brought from oil- and coal-containing rocks in the form of hydrocarbons.
It is most likely that in nature, diamond crystallization occurred under different conditions. One part of the diamonds was formed during explosions in the intermediate centers described above, the other - from a magmatic melt in the deep zones of the earth's crust.
In addition to the finds of diamonds in kimberlites, single diamonds were found in fragments of pyroxene-garnet and garnet-olivine rocks found as inclusions in kimberlite pipes.
The degree of diamond potential of individual kimberlite bodies largely depends on their structural and spatial position. Most of them gravitate to the junction zones of syneclise (extensive gentle deflection of the layers of the earth's crust within the platform) and anteclise (extensive gentle uplift of the layers of the earth's crust within the platforms), where large faults apparently developed. The specific reasons for the spatial distribution of diamond-bearing and non-diamond-bearing pipes have not yet been clarified and require detailed research.
Within some folded areas (Urals, Eastern Australia, Kalimantan), diamonds were found only in placers. There are no kimberlites. The primary sources here are considered to be ultramafic rocks, mainly peridotites. All known diamond-bearing bodies of this type are of no industrial importance.
Diamond deposits in the Republic of Sakha Yakutia
Diamonds from Yakutia have now taken a firm place in the country's economy. In 1949, only the first diamonds were found on the river. Vilyue, and already in 1954 - the first cmberlite pipe with diamonds. To date, large primary diamond deposits have been discovered, such as the Mir, Aikhal, and Udachnaya pipes.
Every year, diamond production increases significantly.
Kimberlite pipes of Yakutia
On the territory of Yakutia, bedrock and placer rocks are known diamond deposits. The only primary sources of diamonds in Yakutia are kimberlites. They are located along the marginal parts of the Siberian Platform at the junction of large structural and tectonic elements
(Anabar anteclise and Tunguska and Vilyui syneclises, Anabar anteclise and the Verkhoyansk and Leno-Anabar troughs). Kimberlite pipes in these zones often show a linear arrangement, indicating their connection with zones of deep faults (disturbances in the earth's crust).
Five areas of development of kimberlite bodies are very clearly distinguished. They differ from each other in their geological structure, varying degrees of diamond content of kimberlites, their composition, and sometimes age.
Malo-Botuobinsky district. This area covers the basin of the well-known river. Malaya Botuobiya (a tributary of the Vilyuya River) and is characterized by a rather simple geological structure. The most ancient rocks exposed on the surface are the gypsum-bearing marls of the Upper Cambrian. These deposits are replaced by sandy-carbonate and clayey-carbonate rocks attributed to the Lower Ordovician. The latter are widespread and are the main ones in the geological context of the region. The eroded surface of the Lower Paleozoic rocks is overlain by sandy deposits of presumably Carboniferous age and continental sandy-clayey deposits of the Lower Permian. Both of them are preserved in the form of small spots in the north-west of the territory.
The Lower and Middle Paleozoic deposits are intruded by igneous rocks of the trap complex, attributed to the Triassic.
Mesozoic deposits are represented by continental sandstones and conglomerates of the Lower Liassic, lying on the eroded surface of all the above-mentioned older sedimentary and igneous rocks. The formations of the Lower Liassic are overlain by coastal-marine clayey-calcareous-sandy deposits of the Middle Liassic.
At the base of the Mesozoic section lie Ratleyassic sand-gravel-pebble deposits and kaolinite clays. They are known in the basin of the middle reaches of the river. Irelyakh, where they were preserved in the form of a small spot on a flat interfluve composed of Lower Ordovician carbonate rocks.
Quaternary deposits of various origins are widely developed in the area.
The primary diamond deposit in this area is the well-known Mir pipe, discovered in 1955. By the nature of the geological structure, it is a vertically extending pipe-shaped body, composed of brecciated rock, consisting of fragments of kimberlite itself and various inclusions of other rocks and minerals; in plan, the pipe has the shape of an irregular ellipse, elongated in the northwest direction 29). With depth, the diameter of the tube decreases. It is made of kimberlite breccia - a rock consisting of fragments and grains of olivine, pyrope, ilmenite, chrome diopside, serpentine, inclusions of related rocks (altered peridotites with pyrope, olivinites, serpentinites), rock fragments pierced by a pipe, and foreign inclusions (mainly carbonate Paleozoic rocks) and a cementing groundmass consisting of a fine-grained aggregate of serpentine and carbonate. the amount of clastic material fluctuates in pre-tubes 80%. The kimberlites of the near-surface part of the Mir pipe are greatly altered and form a number of zones that differ in the nature of decomposition and color.
The upper part of the pipe is represented by destroyed kimberlites. In the exploration pits, the following section is observed: from the surface to a depth of 1.5 m, an eluvial layer composed of clayey sand and kimberlite gruss with fragments of solid kimberlite, limestone and diabase. These deposits are greenish-gray in color. At a depth of 1.5-2 m, these deposits are replaced by heavily destroyed kimberlite, which is represented by loose and woody rock of greenish-gray, yellow-green, dark green and sometimes
bluish flowers. The rock is rich in blue-green chlorite, pyrope and to a lesser extent ilmenite. With a depth of 4-6 m, kimberlite becomes more massive and gradually turns into dense monolithic rocks.
Based on external features, the Mir kimberlite pipe is distinguished into fine-clastic, coarse-clastic, spherical, dense and other varieties of kimberlite.
Diagram of the Mir tube It has been established that the diamond content in the Mir pipe is significant. Diamonds are distributed throughout the pipe, despite its heterogeneous structure (various varieties of kimberlite). The size of the crystals is also almost the same throughout the tube. Both small and large diamonds can be found here and there.
The Mir pipe, as many believe, was formed in the Middle Triassic (200 million years ago). From then until the present period, it was eroded to a depth of about 300-350 m. The released mass of diamonds in the etholl turned into placer deposits.
In addition to the Mir pipe, four more kimberlite bodies were found in the Malo-Botuobinsky region. However, their industrial value is not the same.
The Daldyno-Alakitsky district is located in the basin of the upper reaches of the river. Markhi (left tributary of the Vilyuya River). The area is composed of a uniform complex of carbonate rocks (limestones, dolomites). In a number of places, these deposits are intruded by sheet intrusions and trap dikes, as well as kimberlite pipes. The latter are grouped in an area whose size is 25X60 km. The most famous and richest are the Udachnaya and Aikhal pipes. The first of the pipes found in Yakutia, “Zarnitsa,” is also located here.
Kimberlites in the Daldyn-Alakit region are represented by two varieties: kimberlite breccia (breccia is a rock consisting of cemented angular fragments) of light gray and greenish-gray colors and weakly brecciated dark green kimberlite of porphyritic appearance.
In total, there are more than two dozen kimberlite pipes in the area. Half of them are diamondiferous. The diamond content in them varies.
The kimberlites in this area appear to be of different ages. The presence of pre-Permian and post-Permian (Middle Triassic) kimberlites is assumed. The kimberlite pipes, from the time of their formation to the present day, have been eroded to a depth of about 200-400 m.
Varkhne-Munsky district is located in the upper reaches of the river. Muna (left tributary of the Lena River). Its geological structure is determined by the location of the area on the southeastern edge of the Anabar anteclise, where carbonate rocks of the Middle and Upper Cambrian emerge on the surface.
To date, more than 10 kimberlite pipes are known here, made of kimberlite breccias, tuffs and porphyritic kimberlites. Inclusions of Cambrian limestones, dolomites, crystalline shales, and mudstones were found in the kimberlites.
The age of kimberlites in the Verkhne-Munsky region is assumed to be Triassic, by analogy with the pipes of nearby areas.
The cutting depth of the pipes in this area does not exceed 200-300 m.
Most kimberlite bodies are diamondiferous.
Oleneksky district covers the basin of the middle and lower reaches of the river. Olenek, the geological structure of the territory is quite simple. Carbonate rocks of the Lower, Middle and Upper Cambrian are developed here, intruded by dikes and sheet bodies of traps and kimberlites. More than 50 kimberlite bodies have been discovered in this area. Most of them are tubes, the rest are veins. The size of kimberlite bodies varies (from 20 to 500 m for pipes and 0.5-5 m in thickness for veins).
Most of the kimberlite bodies are made of porphyritic kimberlites, some are made of kimberlite breccias and kimberlite tuffs. In the kimberlites, xenoliths of Cambrian limestones, traps, crystalline gneisses and plutonic rocks - eclogites and peridotites - were found.
Materials to substantiate the age of kimberlites in the middle reaches of the river. Little deer. With a large degree of convention, we can talk about their Middle Triassic age. In the lower reaches of the river. Olenek collected data indicating a younger - Upper Jurassic age of kimberlites.
From then until the present period, kimberlite bodies in the middle reaches of the river. Deer are cut to a depth of 200-300 m, in the lower - to 1500-2000 m.
The vast majority of kimberlites in this area do not contain diamonds. In the middle reaches of the river. Olenek there are pipes with poor diamond content.
Alda, a certain area of kimberlite development covers the river basin. Chompolo. Cambrian carbonate deposits emerge on the surface here. Seven kimberlite pipes are known here, which in composition differ sharply from the kimberlites of the considered areas. They are characterized by a high content of pyrope, chrome spinels and chrome diopside. A characteristic feature of the Aldan kimberlites is the almost complete absence of ilmenite in them. Olivine is almost completely replaced by serpentine. The pipes of this area have not yet been sufficiently studied and there is no material available on their age and depth of cut. No diamonds have been found in them yet.
Placers on the territory of Yakutia are widely developed. However, rich placers are rare.
The following are known among diamond placers: ancient placers formed in distant geological periods and having no connection with the modern topography of the earth's surface. Clastic material and diamonds in them are usually cemented to form hard rocks (fossil placers). Young placers are associated with modern relief.
Among the ancient placers on the territory of Yakutia the following are known:
Permian placers(formed 270-300 million years ago). They are represented by thick (up to 13 m) conglomerates (cemented clastic rocks with rounded fragments). There are few diamonds in these placers, they are difficult to mine and therefore are unlikely to be of practical interest.
Rhet-Liassic proluvial placers have been preserved to this day in the depressions of the Malo-Botuobinsky region. The placer is small: 1.5-2.5 km wide and about 5 km long. The thickness of the placer reaches 0.1-2 m in the peripheral part and 30 m in the central part. Diamond concentrations vary in different areas. The highest diamond contents are typical for the lower parts of the placer. The placer is of industrial importance.
Jurassic coastal-marine Diamond placers were discovered in the lower reaches of the river. Lena. They are confined to conglomerates of small thickness (0.3-0.6 m). The placers have not been studied in sufficient detail. They have not been tested for diamonds. However, one cannot count on great prospects here. The richest areas of the ancient coastal strip, once located closer to the primary sources, have already been eroded, and the remaining areas of diamond-bearing horizons are insignificant in thickness and are covered by a thick layer of non-diamond-bearing rocks.
Young placers of Yakutia are more important industrially and are more widespread. Among them are:
Paleogene-Neogene placers confined to the so-called “watershed” pebbles. The latter are the remains of ancient river beds. They have little connection with modern rivers. Placers of this age are widely developed in the middle reaches of the Markhi and Tyunga rivers and on the left bank of the lower reaches of the river. Lena.
The pebbles to which the placers are confined lie on flat watersheds and reach in thickness
1-8 m. The pebbles are represented by rocks that are resistant to destruction (quartz, silicon, quartzites), which indicates their repeated redeposition, as a result of which weak local rocks completely collapsed and turned into sand and clay. Placers of this type are characterized by varying degrees of diamond content. They deserve further study, since industrial placers may be found here.
Placers of Quaternary age are confined to the valleys and terraces of modern rivers, to ravines, slopes and watersheds. The peculiarities of these placers lie in the fact that each morphological type clearly records a certain element of the earth's surface. For example, terrace placers are confined to deposits of high terraces, channel placers - to river beds, spit placers - to river spits, valley placers - to floodplains and lower river terraces.
Among Quaternary placers, eluvial, deluvial, deluvial-alluvial and alluvial genetic types are distinguished. Placers of alluvial origin predominate.
Eluvial placers are formed on diamond-bearing kimberlite pipes. They have a small thickness (from 1 to 4 m) and are represented by products of destruction of kimberlites. Placers of this type are known at the Mir, Udachnaya, Aikhal, and other pipes. Diamonds are scattered throughout the entire mass of sediments. Somewhat higher concentrations were noted in its lower part.
Deluvial placers are distributed along the slopes near kimberlite pipes. They are represented by clayey, loamy and sandy loam deposits containing crushed bedrock. The thickness of the deposits is from 0.3 to 2 m. Diamonds are concentrated mainly in the lower horizons of the placer. The diamond content in colluvial placers is significantly less than in eluvial placers, and sharply decreases with distance from the bedrock source.
Industrial placers are known in the area of the Mir, Udachnaya, and Zarnitsa pipes.
Alluvial diamond placers are widespread in Yakutia. They are known in the basin of the upper and middle reaches of the river. Vilyuya, in the river basin
Markhi and Tyunga, in the basin of the left tributaries of the river. Lena in its lower reaches, in the basin of the Olenek and Anabar rivers.
Industrial placers are established in the basin of the Irelyakh, Malaya Botuobiya, and Daldyn rivers.
Among alluvial diamond placers, channel, valley and terrace ones stand out.
The most common and best studied type is channel placers.
The source of alluvial Quaternary placers are primary deposits and more ancient placers.
Terrace placers are confined to alluvial accumulations of I, II, III, IV, V and VI terraces above the floodplain, the height of the platforms ranging from 10-15 to 70-80 m above the water level in the channel. Diamonds in these deposits were found along all the rivers of Western Yakutia, where valley diamond-bearing placers are developed, but almost everywhere they are characterized by insignificant concentrations of diamonds. Exploration work on the rivers Vilyui, Markha, Malaya Botuobia, Molodo, Syungyude, Motorchuna and others has established a natural decrease in diamond content from the lower to the upper terraces. The most enriched are the placers of terraces I and II above the floodplain.
Currently, industrial concentrations of diamonds are known only for terrace placers of the river. Malaya Botuobia and its left tributary of the river. Irelyakh.
The structure of terrace placers is very similar to most of the diamond-bearing rivers of Western Yakutia. On the raft there is a layer of diamond-bearing pebbles with a thickness of 0.3 to 4 m. It is covered by unproductive sands and loams, the thickness of which ranges from 2-3 to 10 m. Diamonds are usually scattered throughout the entire thickness of the pebbles. The lower parts of the pebble alluvium are somewhat more enriched.
Valley placers are characterized by a constant structure and constant thickness of alluvium. They have the greatest industrial value and include placers of the floodplain and the first terrace, the diamond-bearing deposits of which lie 3-4 m below the modern water level. In the thickness of alluvium, two horizons are usually distinguished: the upper one is poor in diamonds or does not contain them at all), forming the so-called “peat”, and the lower one is the productive horizon, making up the so-called “sands”. Valley placers in Yakutia are widespread. They are known in the basins of the Vilyuya, Markhi, Tunga rivers, along the left tributaries of the river. Lena in its lower reaches, as well as in the basins of the Olenek and Anabar rivers. However, industrial concentrations are known only in the area of the Mir and Udachnaya pipes. Slightly higher diamond contents were noted in the valley placers of Markhi, Motorchuny, Molodo and others.
Channel placers in Yakutia are very widespread. They are the most well studied. Diamonds have been found in most rivers in the river basin. Vilyuya in the south and a number of rivers flowing directly into the Arctic Ocean. However, despite such a wide areal distribution of diamonds, riverbed industrial placers are established only in the river basin. Lesser Botuobia. Increased diamond content noted in the river basin. Markhi and other rivers.
The study of a large amount of material on the channel placers of Yakutia made it possible to outline some patterns in their structure and distribution,
Placers with increased concentrations of diamonds are located in close proximity to eroded primary and more ancient placer deposits, and the enrichment areas are not very large - from 5 to 10 and less often up to 25 km.
Diamonds are concentrated in areas of the riverbed where the highest speeds of watercourse currents occur.
The Yakut placers are characterized by extreme unevenness in the distribution of diamonds. Areas that are very enriched are replaced by areas that have very poor conditions. This is mainly due to the sharply changing dynamics of watercourses, due to the large difference in river water flows in different periods of the year. In winter, rivers freeze to the bottom and dry up in summer, but at the same time, in the spring after the snow melts and in the summer after heavy rains, there are large floods when the water in the rivers rises to 6-8 m, and sometimes more.
Diamond mining and deposits in Africa
1867 marked the beginning of African diamond history. This year, the son of Boer farmer Daniel Jacobs, playing with friends on the banks of the river. Orange, near Hopetown (South Africa), found a white pebble and brought it home. Jacobs' neighbor Schalk Van Niekerk saw this pebble and asked the owner to sell it to him. Jacobs did not agree to take money for the stone and simply gave it to his neighbor. Niekerk showed the stone to traveling salesman John O'Reilly, who agreed to sell it on the condition that he receive half the price. But O'Reilly could not find a buyer for a long time. Finally, the private commission agent Lorenzo Bayes in Kohlsberg bought the stone and sent it for analysis to the mineralogist Atherston in Grahamstown. Atherston determined the diamond to be 21.73 carats. With O'Reilly's consent, Atherston sold the stone for £500 to the President of the Cape Colony, Budhaus, who sent the diamond to the Paris exhibition.
But for a long time he was not given any importance from Africa. However, in 1869, a shepherd found a new diamond near the Zandfontein farm. It was a beautiful white stone weighing 83.5 carats, later named the "Star of South Africa" or "Dudley". Van Niekerk bought the diamond from a shepherd for 500 rams, 10 bulls and one horse, and he sold it to the Lilienfeld brothers in Hopetown for £11,200. The brothers resold the stone to Countess Dudley for 25 thousand pounds sterling. This diamond served as an impetus for the fact that in the area of the river. A mass of enterprising people who dreamed of getting rich quickly poured into Orange. The diamond rush has begun. In 1870, on the banks of the river. Vaal geologists discovered a rich diamond-bearing placer.
In the same year, diamonds were found in other places in South Africa. They were first discovered at the Jagersfontein farm, then at the Dorstfontein farm, and somewhat later at the Bultfontein farm. Moreover, the diamond was found in the cement that held the bricks together in the wall of this farm. In 1871, a very rich diamond deposit was discovered, which was first named Kolberg Kopje, and later renamed Kimberley - in honor of the English Minister of Colonies. Hence the name of the bedrock in which the diamonds were discovered - kimberlite. Kimberley became the center of the diamond mining industry in South Africa.
In 1890, the Wesselton diamond deposit was discovered 6 km from Kimberley. In 1902, diamonds were found in the Transvaal at the new Premier mine. It was here, on January 25, 1905, that the world's largest diamond crystal weighing 3106 carats, or 621.2 g, called "Cullinan", was found.
In 1925, placers were discovered in Little Namaqua Land, and in 1926, rich placers were discovered in the Lichtenburg area.
In 1887, diamonds were discovered in British Guiana (South America) while panning for gold on the river. Puruni. But industrial mining here began in 1890, when diamonds were found on the river. Mazaruni. From 1890 to 1910, 62,433 carats of diamonds were mined in British Guiana. In 1924, a rich placer was discovered near the river. Yuvang - a tributary of the river. Potaro, which significantly increased diamond production in the country.
The beginning of the 20th century was marked by the discovery of new major diamond deposits. And the first role again belongs to Africa.
In 1903, the first diamonds were discovered in the Congo on the river. Munindele - a tributary of the river. Lualaba, and in 1910 - in the river bed. Kiminina, near the Mai-Munene waterfall, then diamonds were found near the Chikapa and Luashilla rivers (tributaries of the Kasai River). Rich diamond placers along the river were discovered in 1919. Bushimai are still in use today. Systematic diamond mining in the Congo began in 1913.
In 1907, diamonds were discovered in Angola, in the river basin. Kasai and its tributaries. This is essentially a continuation of the deposits of the diamond-bearing region of the Congo. Diamond mining in Angola began in 1916.
Diamonds from the Republic of South Africa gave impetus to the search for them in other African countries. Exploration was especially intensive in South-West Africa. In 1908, during the construction of a railway in the Namib Desert near Luderitz Bay, a black worker found diamonds. They were subsequently found in other places in South-West Africa. The deposits, mostly alluvial, are located along the Atlantic coast from Conception Bay in a southerly direction with a length of 500 km. All the country's major diamond mining enterprises are located in this area.
In the 60s of this century in South-West Africa, diamonds were discovered on the seabed of the coastal strip of the Atlantic Ocean and their mining was organized in the coastal strip from the borders with Angola (Kunin River) to Cape Columbine.
1912 gave the world another diamond-rich country on the South American continent; diamonds were discovered in Venezuela, in the river basin. Caroni. Industrial development here began in 1925.
1930 and 1943 New diamond deposits were discovered in the state of Bolivar, adjacent to British Guiana and Brazil.
In 1910-1912 they were discovered in Tanganyika in the Kwimba region near Mabuki, south of Lake Victoria, then near Shinyanga and on the Iramba plateau. Industrial mining in Mwadui began in 1925, and in the Shinyanga region - in 1928. In 1940, the rich Mwadui kimberlite pipe was discovered in the village of Lukhombo.
In 1915, diamond deposits were discovered in Equatorial Africa. The first diamonds were discovered near Ippi in Ubangi-Shari, in 1928 - in the Bria area, where mining began in 1931. In 1936, diamonds were found in the river basin. Sangi.
The history of the diamond mining industry in Ghana begins in 1919, when on the river. Diamond deposits were discovered in Birim. In 1922, a rich diamond-bearing area was found on the river. Bonza and in the river basin Birim.
Diamond production in the country increased over the year from 215 to 1,000,000 carats.
In 1930, the director of the Geological Survey of Ghana, Junner, discovered the first diamonds in Sierra Leone in the Bafi and Sewa river basin. In 1931, diamonds were discovered in the river basin. Moa. In 1934-1935 Diamond placers were discovered on the territory of Guinea, in the basin of the upper reaches of the river. Moa, then - on the territory of the Republic of Ivory Coast.
In the vastness of Russian soil, the first diamonds began to be found in the eighteenth century. At this time, Russia is the largest supplier of the world's most precious stone. Large diamond deposits are located in the snowy regions of the country. The largest of all of them is the one located in Yakutia. It is Yakut diamonds that are considered one of the most expensive in the world.
Where it all began
Until the 1930s, no one thought about making diamond mining industrial. It was during this period of time that a researcher named Vladimir Sobolev put forward his hypothesis that the Siberian platform was geologically very similar to South Africa.
It was known that Africa had quite large deposits of diamonds. This meant that there was a huge chance that the land above the Siberian platform would also be rich in deposits of expensive stone.
After the war was over, several expeditions went to Siberia, the task of which was to find out whether this land really contains huge diamond deposits and deposits? In 1949, the first diamond was found, and after five years, the first primary diamond deposit was discovered on the territory of the still Soviet Union. They gave it the name “Zarnitsa”. A year later, geologists found another deposit - a kimberlite pipe, which was named “Mir”.
Initially, precious minerals were mined from the deposit by open-pit mining. But gradually the quarry deepened, and the extraction of the fossil mineral had to be done underground.
Let's talk about diamonds in more detail
The word “diamond” comes from the Greek word “adamas”, which translated into Russian means “indestructible”, “invincible”. This mineral is formed by crystalline modification of native carbon.
Diamonds are the hardest minerals in the world. This property is provided by the strongest covalent bonds between atoms, the angle of inclination of the smallest particles in relation to each other, as well as the special structure of these precious stones.
Diamond crystals can have a variety of shapes. The main ones are:
- octahedron;
- tetrahedron;
- rhombic dodecahedron;
Whatever the shape of the crystal, it can have a smooth surface or plate-like stepped edges. It is also possible to have rounded surfaces with various accessories.
Crystals can have both simple and complex combined shapes. They can be flattened or elongated, twins of fusion or germination, which are determined by the spinel law.
The variety of diamond depends on its polycrystalline formations:
- bead - fused small faceted crystals or grains of various shapes. Their color can be gray or black;
- ballas are spherulites, the structure of which is radial-radiant;
- carbonado - formations that can be of several types: cryptocrystalline, dense, slag-like porous, with an “enamel” type surface. Each of them consists mainly of tiny diamond grains, not exceeding a size of 20 microns, which are tightly fused together;
Precious natural minerals can come in a variety of sizes - from microparticles to large, massive stones of several hundred carats. One carat is equal to two tenths of one gram.
As a rule, the stones most often encountered during mining are those whose weight ranges from 0.1 to 1 carat. Large weight specimens are, unfortunately, quite rare in nature.
Chemistry of precious minerals
| Formula | C |
| Molecular weight | 12.01 |
| Impurity | N |
| IMA status | valid |
| Class | Native elements |
| Group | Carbon polymorphs |
| Color | Colorless, yellow, brown, blue, light blue, green, red, pink, black |
| Stroke color | Absent |
| Shine | Diamond |
| Transparency | Transparent |
| Hardness | 10 |
| Fragility | fragile |
| Cleavage | Perfect by (111) |
| Kink | Conchoidal to splintery |
| Density | 3.47—3.55 g/cm³ |
| Point group | m3m (4/m -3 2/m) -hexoctahedral |
| Space group | Fd3m (F41/d -3 2/m) |
| singonia | Cubic |
| Twinning | Twins of germination according to the spinel law are common |
| Optical type | isotropic |
| Refractive index | 2,417—2,419 |
| Birefringence | absent, since optically isotropic |
| Optical relief | moderate |
| Optical axis dispersion | strong |
| Pleochroism | does not pleochroate |
| Luminescence | blue, green, yellow, red |
The chemical composition of diamonds is impressive. There is no more complex stone in nature. It contains elements such as silicon, aluminum, calcium, magnesium, sodium, barium, manganese, iron, chromium and even titanium. But the main impurity is nitrogen. Its amount in a mineral plays a very important role and a lot depends on it.
- Type 1 - the nitrogen content in the stone is approximately a quarter of the total volume of impurities. This type is not transparent to ultraviolet radiation;
- Type 2 - nitrogen content is only one thousandth of the total volume. They are called nitrogen-free diamonds.
Physical characteristics of diamonds
In nature, there are both colorless diamonds and those that have their own shade. It is not uncommon to come across minerals that have purple, blue, green, light blue, and pinkish hues. Also often found are stones that shimmer in gray, yellow or brown.
No one has yet managed to make a colored diamond crystal clear, and this process remains one of the most long-awaited discoveries.
Diamonds are characterized by a high refractive index and beautiful shine. The play of different colors in precious stones is due to the presence of a strongly pronounced dispersion effect.
The surprising fact is that the density of each diamond facet is different.
Diamonds are used not only in jewelry
Since no substances harder than diamond have yet been discovered in the natural environment, this particular mineral is actively used in various industries. Diamonds are actively used in working tools that are intended for drilling, sawing, and processing other materials.
No less popular and widely known is the use of diamonds in science and even technology. Those stones that are not selected for jewelry for any reason - be it inappropriate size, shade, opacity, etc., all of them end up in industrial sectors.
In such industries, the properties of diamonds, such as rapid heat conduction, for example, come in handy. An equally important role is played by the amazing hardness of minerals. If a diamond is transparent, then even infrared and ultraviolet light passes through it. It is also very useful in science and technology because it can simultaneously conduct current or not conduct it at all.
Only diamonds can withstand loads that other materials cannot withstand. Due to their super density, diamonds perfectly withstand not only physical pressure, but also chemical and radioactive environments.
Diamonds are very actively used in medicine. Nowadays, science has reached the point where special blades for scalpels with a diamond coating have been invented. Thanks to this innovation, surgeons can make more accurate and smaller incisions.
Diamond capital
In the twenty-first century, the Yakut city of Mirny is considered the diamond capital of the Russian Federation. It is located in the western part of the Yakut land. Back in 1955, at the time of the discovery of the Mir diamond pipe, on the site of the current large city there was only a small tent city in which those who went on the expedition, as well as workers, lived. But after the discovery of a kimberlite pipe and active excavations of a deposit of a precious mineral, less than four years later the city of Mirny became an important city on the map of the country.
Currently, the population of Mirny is about thirty-five thousand people. Almost the entire population of the city is employed in the diamond mining industry. Diamonds are mined in a quarry located very close to the city itself. This facility is one of the largest quarries in the world. Its depth is more than half a kilometer, and its diameter is more than one kilometer.
A serpentine road runs along the slope of the quarry in Mirny. During the existence of the quarry, its length exceeded eight kilometers. This quarry is not the only one in the city. In such objects, diamonds are mined by open-pit mining.
There are also underground mines in Mirny, which are also actively used in the extraction of the precious mineral. In such places, workers work non-stop - in shifts. They are given only two days off a year - New Year and Miner's Day.
If the deposit is rich, then one ton of mined ore may contain nine carats of diamonds. In order to transport the mined ore to the surface, miners use dump trucks, each of which can transport almost one hundred and forty tons of ore at a time, which is approximately four hundred carats of diamonds. Next, the stones are transferred to a special plant, where they are further processed.
Without a cut you are glass, but with a cut you are a million
After the mine, all diamonds are delivered to the sorting center, which also operates in Mirny. The initial assessment of each stone individually and their sorting by weight takes place here. The largest specimens are selected exclusively by hand by specialists.
Specially trained people closely examine each pebble in order to correctly assess its shape, size, and color. This procedure takes place only with multiple magnification of the stone under special devices, such as various magnifying glasses and a microscope. No less important is the quality of the precious mineral and its transparency.
Each stone that comes into the hands of a specialist is carefully examined three times. Up to a dozen stones can fall through his hands within one hour.
After selecting stones suitable for jewelry making, they are sent to the factory, where they are given the optimal shape. Trained craftsmen approach this issue very scrupulously, since each stone is very expensive and it is simply unacceptable to make a mistake here.
The specialist studies how to properly trim the stone in order to leave the largest carat weight and minimize losses.
It is possible to cut a diamond using exclusively specially designed blades that are coated with diamond coating. As long as the diamond has not been processed, it may not be so expensive. But the moment the stone is cut, its price can rise sharply, even millions of times.
Russian leader
It is the Russian company that occupies a leading position in the global diamond mining market. This is a company called Alrosa. The annual diamond production reached almost forty million carats.
This company mines thirty percent of the world's precious minerals. Almost the entire diamond mining industry of the Russian Federation is in its possession.
A large number of quarries and mines that are the property of Alrosa are the only ones on the entire planet and have absolutely nothing in common with the rest of the world’s deposits. The largest volumes of regularly mined raw materials, the strictest selection and the highest quality make the company a serious competitor in the global industry market.
- To keep diamonds safe, you can place them in chests or stoves.
- Diamonds are very common near lava.
- If you plan to dig for a long time, then create a protected and equipped base, with a bed, chests, a stove and, most importantly, a garden for growing food (watered with water blocks and lit with torches).
- Always carry a large amount of wood, a furnace and a crafting table so that the mined iron can be smelted into bars and create a large number of pickaxes.
- If you find diamonds in a lava pool, pour water on it, or place a block on it; if you don't, the diamonds may fall into the lava and be destroyed.
- If you come across a cave, don't go too high as you won't find any diamonds there. Simply cover the passage for future inspection.
- You can survive the attack of any mob underground using barriers. Skeletons are vulnerable at short combat distances; hit their legs when they are behind the fence.
- Always dig a wide hole, even if it takes longer.
- If you don't have food and a sword, or don't want to carry them with you, you can always switch to peaceful mode, as there are no hostile mobs and hunger.
- Don't get too high; you may fall.
- To find out your location, press F3.
- If you want to learn more about ore mining, read here: http://www.minecraftwiki.net/wiki/Tutorials/Mining_Techniques
- Crawl when you are near the edge to avoid falling into the lava, or to avoid falling at all.
- Digging upward is also a dangerous activity. There may be gravel or lava above you.
- Listen carefully while mining ore, you will be able to hear hostile mobs other than creepers. If you're playing on Peaceful difficulty, don't worry about hostile mobs. Dig as much as you want!
- Diamond ore only appears on Y:5 and Y:12.
- If you're digging in the pocket version, then you shouldn't be afraid to dig straight down, as there are no lava pools underground. However, there may be deep caves and ravines, so be careful.
- Mining diamonds requires patience!
- If you see lava or water flows, block them, even if there is a bypass. Who knows, you might find diamonds!
- If you don't want to be disturbed by mobs while mining diamonds, switch to peaceful mode.
- Try to find ravines; these textures often contain a lot of coal, iron, gold and even diamonds.
- Remember the golden rule of ore mining! Never dig straight down or up (you could fall into lava, get attacked by a mob, drown in water, or choke on dust).
- Always create a defense perimeter for your underground base - even leaf blocks will be useful.
- If you're digging in survival mode, don't dig straight down as you'll likely fall into the lava or down a ravine. Try making a ladder.
- Try asking others for help with diamond mining. The more people, the more diamonds you will find.
- Diamonds can only be mined using an iron or diamond pickaxe.
- If you're digging, set up torches to avoid spawning hostile mobs.
- Don't go into dark areas with hostile mobs without a sword, ax or bow/arrow!
- Diamonds are most often mixed with stone, not near lava. It's true that you can find diamonds near lava, but this reduces the amount of diamonds in the veins.
- Fortune III pickaxes increase your diamond search by 4. If you have one, use it to mine diamonds!
- When you find a diamond deposit, carefully study the area around it so as not to simply lose a valuable resource. After all, lava lurks everywhere
- When you play the pocket version, use the first method. You will definitely find gold and diamonds.
- Take food as you will spend a lot of time underground. You won't like it if you lose all your mined diamonds and ores due to starvation.
- Dig down to the root passages, and then up 12 blocks, then mine the ore. You will find additional ore.
- Never carry diamonds with you in case you die. Place them in a chest, preferably in the Ender Chest.
- If you are playing in survival mode, then build a house in the mountains so that you are not attacked by mobs.
- Look around when you find diamonds, some veins contain hidden nuclei.
Diamonds that are mined from kimberlite pipes are the result of underground volcanic eruptions that occurred millions of years ago. Under the influence of high temperatures and enormous pressure, carbon received a strong crystal lattice and turned into a gemstone. Subsequently, the discovery of this property made it possible to establish the production of artificial diamonds. But natural stones, of course, are much more valuable.
Today we will look at how in our country they mine what becomes part of precious jewelry and is the object of desire of any woman.
The photo shows a view of the main quarry of the Udachny mining and processing plant - “Udachny”. Mining operations at the deposit of the same name began in 1971, and over the past 25 years the plant has been a leading enterprise in the Russian diamond mining industry and one of the largest open-pit mines in the world. In 2010, the Udachny Mining and Processing Plant accounted for 33.8% of diamond production in value terms and 12.5% of mining operations out of the total volume of the Alrosa group.
The first large-scale industrial diamond mining began in southern Africa about a hundred years ago. In Russia, kimberlite pipes were discovered only in the middle of the last century - in Yakutia. This discovery laid the foundation for Alrosa, today the world leader in diamond mining. Thus, the company’s forecast reserves are about a third of the world’s total, and the explored reserves are sufficient to maintain the current level of production for 25 years without reducing the quality of raw materials. In numbers, the diamond reserves at the deposits owned by Alrosa amount (according to data published in May 2011) to 1.23 billion carats according to the Russian classification (1.014 billion proven and 0.211 billion probable).
For the last five years, the company has annually allocated from 2.5 to 3.5 billion rubles for geological exploration. In 2011, geological exploration costs amounted to about 4 billion rubles, in 2012 - over 5.36 billion rubles.
At its fields, Alrosa produces about 35 million carats of diamonds per year, being the world's largest producer of this raw material in physical terms: it accounts for about 97% of Russian production and 25% of global production. At the same time, the diamond content in the ore of kimberlite pipes is traditionally low - usually several carats per ton. The Yakut deposits are advantageous in this regard, and are considered one of the richest in content.
In 2010, Alrosa's sales volume of diamonds and rough diamonds amounted to $3.48 billion, and in 2011, according to preliminary data, the company sold $5 billion worth of products - a record figure in its entire history. The company's revenue in the first half of 2011 according to IFRS amounted to 66.15 billion rubles. (+3% compared to the previous year), and net profit increased five times to 26.27 billion.
Kimberlite pipes have the shape of a cone, expanding upward, so their development usually begins with open-pit mining. The design depth of the Udachny quarry, shown in these photographs, is 600 m. To rise from the bottom of the quarry to the surface, the dump truck travels along a serpentine road about 10 km long.
And this is how mining is carried out in quarries. The drilling rig makes a hole into which the explosive is placed (the photo shows the laying process). By the way, although diamond is the hardest mineral, it is quite fragile. Therefore, during blasting operations, gentle technologies are used to preserve the integrity of the crystals as much as possible. After the explosion, the rock fragments are loaded into dump trucks and transported to the processing plant.
The company's main enterprises are located in Western Yakutia, on the territory of four regions of the Republic of Sakha (Yakutia) - Mirninsky, Lensky, Anabarsky, Nyurba - in one of the most severe regions of the planet, with a sharply continental climate, a large temperature difference, in the permafrost zone. In Udachny, winter lasts up to 8 months; winter temperatures sometimes drop to -60 C.
Therefore, most of the equipment is made to order - these are machines adapted to work in low temperature conditions. As a result, work at the fields is carried out all year round in all weather conditions. Quarry work simultaneously involves a large number of equipment - wheel loaders, dump trucks, excavators. There are only about 300 heavy-duty dump trucks in the Alrosa fleet, with a carrying capacity from 40 to 136 tons - mostly BelAZ, there are also Cat and Komatsu.
After reaching a certain depth, reserves within the quarry are exhausted, and open-pit mining becomes unprofitable. On average, quarries are developed to a depth of about 600 m. However, kimberlite pipes lie underground to a depth of 1.5 km. A mine is being built for further development. Underground mining is more expensive than open-pit mining, but it is the only cost-effective way to reach deep-seated reserves. In the future, Alrosa plans to significantly increase the share of underground diamond mining. The company is now completing open-pit mining of the Udachny quarry and, in parallel, is constructing an underground mine. It is expected to launch in 2014.
The cost of switching to underground diamond mining is estimated at $3–4 billion, but in the future this should lead to cost reductions. Largely due to the construction of underground mines, Alrosa’s debt by the acute phase of the crisis in 2008 increased by 64% to 134.4 billion rubles. But the state did not leave the company in trouble: it was included in the list of systemically important enterprises, non-core gas assets were bought by VTB for $620 million, and when the demand for diamonds fell, Gokhran began to buy Alrosa’s products.
The controlling stake in Alrosa (51%) is federally owned (from 2006 to 2008, 10% of this stake belonged to VTB), 32% of the shares belong to the government of Yakutia, 8% are controlled by the uluses of this federal subject. In April 2011, the company was transformed from a closed joint stock company to an open joint stock company in order to be able to raise funds on the market. Since the middle of last year, Alrosa shares have been traded on Russian exchanges, but the volume of transactions on them is small due to low liquidity (only shares of minority shareholders were listed on the exchange). In the fall of 2011, Nafta-Moscow of Suleiman Kerimov became one of Alrosa’s shareholders, buying up about 1% of the company’s shares on the market.
When you hear the word “diamond mines,” you involuntarily imagine a beautiful picture: a cave, within the walls of which precious stones shimmer with all the colors of the rainbow. In fact, a diamond mine is not the most romantic place on earth. The walls do not sparkle with a diamond shine, and looking at the ore, it is generally difficult to imagine that the future “best friends of girls” are hidden in it. The photo shows workers in one of the ventilation horizontal openings of the future underground mine, depth - 380 meters.
The construction of mines takes place in unique mining and geological conditions. In addition to permafrost, it is complicated by aggressive groundwater, which, due to high mineralization, can not only erode the walls of mine workings, but also corrode (!) tires of dump trucks. In addition, at Alrosa’s fields there are bitumen and oil shows, which also complicate diamond mining.
In parallel, construction of ground-based facilities of the future mine is underway - for example, ventilation and heating units. The Udachny underground mine will become one of the largest in the world - its productivity is expected to be 4 million tons of ore per year. This is not the company’s first underground mine: since 1999, Alrosa has been working at the Internatsionalny mine. In addition, in August 2009, the company commissioned the Mir underground mine.
When all mines reach full capacity, the share of underground mining in Alrosa's total operations is expected to rise to 40%. In total, in Russia the company mines diamonds at 9 primary and 10 alluvial deposits located in Yakutia and the Arkhangelsk region. In addition, the company owns the Catoca diamond mining enterprise in Angola, together with the local state-owned company Endiama.
What will underground mining at Udachny look like in 2-3 years? For example, here is a photograph of the already operating Mir mine. The extraction of diamond ore underground is carried out mainly by combine mining (pictured). The company's specialists are also studying the possibility of using blasthole blasting, traditional for mining - when the rock is destroyed with explosives placed in drilled holes. Then the scheme is the same: loading machines pick up the ore and transport it to the surface, from where it goes to the processing plant. Now we will go there too.
The initial stage of beneficiation of diamond ore looks the same as for any other mineral. Initially, the factory receives large pieces of rock up to several meters in size. After coarse crushing in jaw or cone crushers, the ore is fed to wet autogenous grinding mills (pictured), where rock fragments up to 1.5 m in size are crushed to a size of 0.5 m or less using water.
At the next stage, spiral classifiers separate the raw materials depending on their density and size. The operating principle is very simple. Water picks up small particles and carries them down the drain. Large particles (up to several centimeters in size) can no longer be carried away by water - they settle in the lower part of the tank, after which the spiral lifts them to the top.
The next stage of enrichment is the roar, so named for the noise that accompanies the work. A “screen” is a huge vibrating sieve with holes of different sizes, which allows you to sort raw materials into different fractions. Separation of raw materials into size groups is necessary, since in the future each of them will be enriched in different ways.
Now we need to somehow isolate diamonds from small pieces of ore obtained after crushing. Medium-sized pieces of ore are sent to jigging machines and to heavy-medium concentration: under the influence of water pulsation, diamond crystals are isolated and settle as a heavy fraction. The fine “powder” passes through pneumatic flotation, during which, interacting with reagents, small diamond crystals adhere to the foam bubbles.
At the next stage, all raw materials will go through the main procedure - X-ray luminescent separation (RLS).
It’s just not possible to show what happens inside the separator during its operation: the radar principle is based on constant x-ray radiation. Looking inside while the separator is operating is, to put it mildly, unsafe. If described in words, the method is based on the unique property of diamond - it is the only mineral that luminesces in X-rays.
Crushed ore, irradiated with X-rays, constantly moves along the conveyor belt inside the separator. As soon as it enters the irradiation zone, photocells record the luminescent flash and the air flow “knocks out” the sparkling fragment into a separate tank.
Of course, the air flow inside the separator cannot separate just one small crystal - a certain amount of waste rock is also sifted out along with it. In fact, the entire process of ore beneficiation is aimed only at minimizing the amount of this “empty” material and then facilitating manual processing. Moreover, “manual” in the literal sense of the word: specialists select crystals, clean them and carry out the so-called “final finishing”.
No matter how popular the desire to automate all production processes is now, it is absolutely impossible to do without the human factor in diamond mining.
From the final finishing shop, all rough diamonds are sent to the Sorting Center in Mirny. Here, raw materials are divided into main groups and given an initial assessment, after which they can be sent for sale through the Alrosa Unified Sales Organization.
By the way, about half of Alrosa’s products are sold outside of Russia. Until recently, the company sold its diamonds to the world market using the services of the monopolist De Beers. However, at the beginning of 2009, they stopped cooperation and Alrosa began reorganizing its sales system, providing for sales under direct contracts and an equal approach to foreign and Russian buyers, developed its customer base and introduced the practice of “long” contracts.
In general, raw materials from each of the deposits have their own distinctive characteristics. Experienced experts, when looking at a diamond, can determine which mine it came from. But this only applies to general signs. No two diamonds are alike. Therefore, there are no organized exchange trades in diamonds, for example, like gold or copper - this is not a standardized product, each stone has unique characteristics.
This uniqueness significantly complicates both sorting and evaluation. When assessing, experts take three characteristics as a basis: size, color and purity (absence of inclusions inside, transparency). The most expensive stones are “pure water”, absolutely transparent and have no pronounced color. Each of the characteristics has different gradations. As a result, depending on size, color and other parameters, there are about 8,000 possible positions of rough diamonds.
