admin Historically, some newly discovered minerals or their varieties were named after scientists who discovered them (or made a great contribution to mineralogy), or famous statesmen who also made a significant contribution to the development of science or contributed to it.
In case of the name of the chrome variety of chrysoberyl – alexandrite, everything happened a little differently. The mineral was named in honor of Tsarevich Alexander in 1834, who at that time was only 16 years old, and he did not distinguish himself by any special affairs. But as subsequent events showed, ascending the throne on February 19, 1855, and before the tragic events of March 1, 1881, Emperor Alexander II left a very noticeable trace in the history of Russia. It was he who received the nickname as the “Tsar Liberator”, abolishing serfdom in 1861. In the era of his reign, the economy developed rapidly, more than 20 thousand kilometers of railroads were built in a short time, Russia turned into a leading industrial power, etc. So it was not in vain that his name was immortalized in the name of the most amazing Russian gem.
Discovery history
The history of the discovery of Russian Alexandrite is unusual and extremely confused. The issue of the priority of the discovery was considered by various researchers, and in our opinion, the circumstances of the discovery and all participants in those events were most fully considered by Semenov and Karl Shmetser. It is probably difficult to add some new facts to the above studies, so we touched on only some of the most controversial moments in this really detective story.
Many publications and reference books still indicate the date of discovery of alexandrite in 1842 and the priority of the famous Finnish mineralogist Niels Gustav Nordensköld. Undoubtedly, the first publication with a description of the mineral called “alexandrite” appeared in 1842 in the first volume of “Notes of the Imperial St. Petersburg Society” under his authorship. Of course, he did not find it himself, for the first time N. Nordenshchild visited the Urals only in 1849. According to various sources, the samples of alexandrite were given to him by Count Lev Alekseevich Perovsky, who was a passionate collector and lover of mineralogy, and at that time former Gofmester of the Russian Imperial Court, senator and head of the Department of Dependencies. Count L.A. Perovsky, less than a year after the discovery of emerald deposits, makes an “inspection” trip to the area of emerald mines to inspect emerald mines, financed from the Departments of ancestors. In 1832, such a journey was very difficult and difficult, but despite all the difficulties, at the end of September 1832, L.A. Perovsky arrived at the emerald mines. Here he not only inspects the work done, but also goes down to the mine at Sretensky mine, and also collects a large collection of minerals, and of course, an unusual mineral fell into his field of vision, which he at first mistook for a low-quality emerald. However, in the evening, he wanted to once again examine in more detail the unusual “emerald” in the flame of a candle. And what was his shock when he saw how the “low-quality emerald” in the light of the candle flame turned into a rich cherry red color. Of course, Count L.A. Perovsky, being a great connoisseur of minerals, immediately realized that in front of him was a new, not yet known mineral.
But Count Perovsky, of course, was not a professional mineralogist and researcher, and all his attempts to independently study the new gem did not lead to anything. In 1833, L.A. Perovsky gave 4 samples of an unknown mineral to the Mineralogical Society in St. Petersburg for research. They were studied by Franz Ivanovich Werth, who first identified an unknown mineral found by Count Perovsky on the Emerald Mines as chrysoberyl.
In parallel, Perovsky sends two samples of this mineral for research to Nils Nordenshild, and later in a letter dated May 24, 1934, another 5 samples. Count Perovsky was so sure that he had a new mineral in front of him, which, without waiting for the results of his study, gives him a name. Since at this time (April 17, 1834) all of Russia celebrated the coming of age as heir to the throne, Tsarevich Alexander, the future Emperor Alexander II, Count Perovsky, wanting to curry favor with the imperial family, calls him the unusual mineral he found – ALEXANDRITE, and under that name presents it to the Tsarevich Alexander on the day of his majority. There is a version that Perovsky, again convinced that he had a new mineral in front of him, sent samples to Nordenscheld with the condition that after the study, the new mineral would be officially named alexandrite.
It would seem that everything is clear, Count Perovsky, during his visit to the Emerald Mines, finds a mineral unknown to him and gives it to Wert and Nordenschild for research. Without waiting for the diagnostic results, he calls the found gem “alexandrite”.
In 1997, Semenov V.B. A letter from Yakov Vasilievich Kokovin to the vice-president of the cabinet of His Imperial Majesty Prince Nikolai Sergeyevich Gagarin was found in the Sverdlovsk Regional Archive, from which it clearly follows that Kokovin found an unknown mineral that Count Perovsky already called “alexandrite”, if you believe the date of the letter on June 16 1834.
It follows from the letter that as soon as Kokovin found an unknown gem, he sends it to the test of Count Perovsky, which could not have happened in June 1834, because if you accept this date, then for 2 months, the new gem has been presented to Tsarevich Alexander and named in it honor “alexandrite.” But it really turns out that the letter was not written in June 1834, but in June 1831, and then everything falls into place.
Naturally, such an experienced explorer of the Urals and a great lover of minerals, who is constantly at the center of mining operations, could not help but notice the new gem, about which he immediately sends a report to Prince Gagarin and sends a sample to Count Perovsky for determination. Prince Gagarin, apparently did not react to Kokovin’s report. His interests were very far from mineralogy, in contrast to Perovsky, who immediately realized the uniqueness of the find and immediately went on an “inspector” trip to the Urals.
It is completely obvious that Jacob Kokovin should be considered the discoverer of the Ural alexandrites, which is also considered by a number of other researchers. But why, then, was the name of Kokovin so firmly forgotten by both contemporaries and subsequent researchers, until 2002? Most likely this is due both to the personality of Kokovin and Count Perovsky. There is not much archival information, but they also allow us to state that when Kokovin received a false denunciation of embezzlement of emeralds, it was Perovsky who initiated the audit and the case against Kokovin. It is Perovsky who abducts the so-called “Emerald of Kokovin” and blames Kokovin for everything. Separate archival materials have survived indicating that immediately after the discovery of the emerald deposits, Count Perovsky tried to establish special relations with Kokovin both directly and through dummies in order to have direct access to the most unique samples. However, despite all attempts, Kokovin did not accept the proposals of Count Perovsky, although they promised him considerable benefits. This Count Perovsky could not forgive Kokovin. According to contemporaries, Count Perovsky was not only extremely energetic, persistent and persistent, but also narcissistic, ambitious, cruel and vindictive. Most likely, it was Perovsky who did everything in his power to send a person to jail on knowingly false charges.
As a result of the “investigation” on December 13, 1835, Kokovin was removed from his post and imprisoned, from where he left in 1838 as a seriously ill patient, deprived of orders, ranks, and noble rank. Kokovin died in 1840. Kokovin’s guilt was not confirmed, but nevertheless, contemporaries tried not to mention his name again. Undoubtedly, it is necessary to restore the historical truth regarding this extraordinarily talented and honest man who really was the first to find alexandrite and realized that this was still a gem unknown to science.
A brief geological sketch of the Alexandrite Mines
In the Urals, alexandrite and emerald are found in the same geological formations (micaceous), and often in the same mineral associations. In fact, alexandrite mineralization was discovered in half of all known emerald deposits, known within the unique ore region included in the literature under the name “Ural Emerald Mine”.
In fact, alexandrite, was found in 11 deposits of Emerald Mines.
“Druze Kochubey”, with daylight on the left, with artificial lighting on the right. Size 25×16.5×11 cm, weight 5389 grams, consists of 22 tees. Museum them. A.E. Fersman. Photo by Evseev A.A.
Alexandrite Gemology
The chemical composition of alexandrite is BeAl2О4, also contains up to 1% Fe2O3 and up to 0.4% Cr2O3, and impurities of some other elements – titanium, vanadium, cobalt, nickel, manganese, copper. Basic physical properties: hardness (on the Mohs relative scale) – 8-8.5, density – 3.644-3.763 g / cm3. The refractive index along different crystallographic axes is from 1.744 to 1.758 (ng = 1.753-1.758; nm = 1.777-1.753; np = 1.744-1.748). Birefringence (ng – np) = 0.007-0.011. The dispersion is 0.009-0.011. Pleochroism is abnormally high in three directions (trichroism). On the np axis, the color of the stone is red, red-violet, on the nm axis – greenish-yellow along the ng axis – green, bluish-green.
A special property of alexandrite is the “alexandrite effect”, which created special popularity for it – its ability to change color, depending on what kind of light source it is illuminated. Such a color change is explained by the presence of Cr + 3 in the crystal lattice, replacing Al. The “Alexandrite effect” is a consequence of the strictly determined position of the bands in the absorption spectrum.
In Russia, in gemological practice, the concept of “reverse” is used, that is, the sum of the brightness values of green and red colors, expressed as a percentage. The reverse coefficient can vary from 10 to 90% or more. With a strong (80-90%) color change, a slight color tone of the original tone remains, with a weak (10-20%) a slight color tone of a new tone appears. The Mariinsky field is subject to the Technical Conditions (TU 9645-002-26420171-94), which divides the color change into 3 groups, 1- with a strong effect (reverse 70-100%), 2- with medium (40-70%), 3- with a weak effect (10-40%). Accordingly, for each of these groups there are standards for sorting alexandrite products. The company also distinguishes three groups of cleanliness. The first includes transparent stones with inclusions barely visible to the naked eye. The second – transparent stones, with a network of desires in separate areas visible to the naked eye. To the third group of purity – stones are partially transparent, with inclusions in the entire volume, visible to the naked eye.
Alexandrite has always been highly valued. Like any gem, the price of it depends on its size, color, purity (defect-free). In the case of alexandrite, the color of the stone is also added here under various lighting conditions, its purity and saturation. Again, in the case of the Ural alexandrite, it is rare. Both in Russia and in the International Gemological Community, one can find various price lists for alexandrite. However, it should be recognized that they all serve only as rough indications.
The future of Ural Alexandrite
What are the prospects for rare color-changing Alexandrite from Russia? What are its reserves and forecast resources? Currently, there are no unequivocal answers to these questions, moreover, there are completely different estimates, both for the extraction of alexandrite in general, and for the output of cut raw materials, and for its reserves in the bowels. Moreover, these data often contradict each other. We will not discuss all points of view, we will focus only on one, in our opinion, the most justified.
Since the beginning of work on emerald (and, accordingly, on alexandrite) from 1831 to 1921, according to official statistics, about 5 tons of alexandrite raw materials have been mined, including more than 82 kg (410000 carats) of cutting quality, which corresponds to a yield of 1.6%. This value as a whole is very close to the current data of OA “Mariinsky mine” on the extraction of cut diamonds from crystal raw materials.
It is more difficult to estimate production over the next 100 years (from 1921 to 2019). Since for a considerable period (1921-1971) there are no data at all in the open press on the extraction of alexandrite. In reality, of course, the extraction of alexandrite (or simply its associated mining) did not stop all this time.
In the years 1921-1971, according to our estimation, about 600 kg of crystal raw materials of alexandrite (about 10 kg of cut-off material) were mined.
In the years 1972-1992, in our estimation, 240 kg of crystal raw materials of alexandrite (4-5 kg of cut material) were mined.
Thus, for the entire period 1831-1992. 5840 kg of crystalline raw materials were extracted, including 97 kg (485,000 carats) of high-grade alexandrite. According to Laskovenkova A.F. and Zhernakova V.I. (Gems and Gemology, 1995), reserves of emeralds, and, accordingly, alexandrites, are 30–35% (i.e., one third). Accordingly, the resources of alexandrite in the main deposits as in 11680 kg of crystalline raw materials, incl. 194 kg (970000 carats) polished.
Why, then, only one field works, and even those fields for the development of which the licenses were taken do not work? In reality, despite such significant potential only in alexandrite, the results of geological and economic calculations show the unprofitable operation of the Emerald Mine deposits in the Urals today. Of course, there are a number of objective factors. 1 – The main reserves (resources) of alexandrite (including emerald), and this is about 80%, are located at depths of 100-500 m from the earth’s surface. 2 – All deposits of the Emerald-bearing strip are characterized by very complex mining and geological conditions, both in terms of structure and water cut of deposits. This, in turn, very significantly increases the cost of exploration and mining, and, accordingly, the cost of production. Nevertheless, the situation does not look deadlock, at present there is a significant number of proposals aimed at changing the current situation (such as changes in legislation and the tax burden on enterprises, the introduction of new technologies in the development of deposits, extraction of raw materials, etc. .)
