What is the difference between serpentine and malachite?
Justification. Since its discovery, malachite has not been considered a rare stone, but increased demand has led to the depletion of most deposits, and counterfeits are increasingly found on the markets [1, 2]. Goal — demonstration of methods for determining the naturalness of malachite and popularization of knowledge about the variability of fakes and imitations. Methods It is quite easy to identify fake malachite. A series of simple manipulations will allow you to establish the naturalness of the stone. You need to pay attention to the following criteria:
- Mass of stone. This aspect allows you to identify plastic and glass counterfeits. It should be noted that malachite is heavier than most other natural minerals used to create an imitation of the real mineral.
- Dullness. Natural stone does not shine through in the sun. It lacks transparency, the surface is matte, with little shine. A simple way to check is to shine a flashlight on the stone or raise it to the sun. If light passes through it, then this is a fake gem.
- Heterogeneity. Malachite mined in African countries has beautiful, even rings, but the patterns on two gems cannot match. The effect of similarity can be achieved only by making the stone yourself, in an attempt to realize its exact imitation. To check the gem, you need to examine the samples presented nearby. The pattern of the concentric rings will vary slightly, but will vary. If the gems are similar to each other, then this is a fake.
- Shades. The differences are present not only in the pattern, the color of the stone itself says a lot. The master will use various paints when creating an imitation of malachite. For example, a coil can be “touched” in order to sell it under the guise of malachite. This is a natural stone, but its price is much less. The key difference is the shade: malachite has a deep emerald green, while serpentine has a marsh color.
- If you have a stone and you doubt that it is real malachite, you can check the stone by the color of the line by scratching it (Fig. 1). To do this, however, you will have to ruin one bead. The color of the malachite streak will be green – from light turquoise to very dark green. The color of the pseudomalachite streak will always be lighter than the stone itself.
- The ammonia and acid test is one of the best tests to determine the authenticity of a stone. Most fakes can be visually distinguished, but high-quality and expensive imitations can be misleading. It is worth considering that experiments will lead to a change in the appearance of the stone, so you only need to work with the back part of the gem or jewelry. The first test involves applying a drop of ammonia to a small area of malachite (Figure 2). The area on natural stone will fade after a few minutes. The ammonia will turn blue. Sometimes you need to wait more than 5–7 minutes; even a natural gem is coated with varnish, which can prevent the drop from contacting the surface of the stone. The second test is to apply acid to the stone. You need to add lemon juice to warm water and then apply it to the gem. The surface should bubble if the malachite is genuine. The reaction time depends on the presence or absence of varnish.
Rice. 1. Determination of the color of malachite trait
Rice. 2. Ammonia test
Do not forget that malachite produced under artificial conditions passes the above-mentioned tests, since it has a similar chemical formula. Unfortunately, there are no methods for determining laboratory stones, so in this case you can only rely on the honesty of the seller.
Results. Verification tests have been proposed to determine the naturalness of a stone.
Conclusions. Buyer awareness of the different types of counterfeit and how to identify it will significantly reduce the number of cases of fraud involving counterfeit malachite.
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Полный текст
Justification. Since its discovery, malachite has not been considered a rare stone, but increased demand has led to the depletion of most deposits, and counterfeits are increasingly found on the markets [1, 2].
Goal — demonstration of methods for determining the naturalness of malachite and popularization of knowledge about the variability of fakes and imitations.
Methods It is quite easy to identify fake malachite. A series of simple manipulations will allow you to establish the naturalness of the stone. You need to pay attention to the following criteria:
- Mass of stone. This aspect allows you to identify plastic and glass counterfeits. It should be noted that malachite is heavier than most other natural minerals used to create an imitation of the real mineral.
- Dullness. Natural stone does not shine through in the sun. It lacks transparency, the surface is matte, with little shine. A simple way to check is to shine a flashlight on the stone or raise it to the sun. If light passes through it, then this is a fake gem.
- Heterogeneity. Malachite mined in African countries has beautiful, even rings, but the patterns on two gems cannot match. The effect of similarity can be achieved only by making the stone yourself, in an attempt to realize its exact imitation. To check the gem, you need to examine the samples presented nearby. The pattern of the concentric rings will vary slightly, but will vary. If the gems are similar to each other, then this is a fake.
- Shades. The differences are present not only in the pattern, the color of the stone itself says a lot. The master will use various paints when creating an imitation of malachite. For example, a coil can be “touched” in order to sell it under the guise of malachite. This is a natural stone, but its price is much less. The key difference is the shade: malachite has a deep emerald green, while serpentine has a marsh color.
- If you have a stone and you doubt that it is real malachite, you can check the stone by the color of the line by scratching it (Fig. 1). To do this, however, you will have to ruin one bead. The color of the malachite streak will be green – from light turquoise to very dark green. The color of the pseudomalachite streak will always be lighter than the stone itself.
- The ammonia and acid test is one of the best tests to determine the authenticity of a stone. Most fakes can be visually distinguished, but high-quality and expensive imitations can be misleading. It is worth considering that experiments will lead to a change in the appearance of the stone, so you only need to work with the back part of the gem or jewelry. The first test involves applying a drop of ammonia to a small area of malachite (Figure 2). The area on natural stone will fade after a few minutes. The ammonia will turn blue. Sometimes you need to wait more than 5–7 minutes; even a natural gem is coated with varnish, which can prevent the drop from contacting the surface of the stone. The second test is to apply acid to the stone. You need to add lemon juice to warm water and then apply it to the gem. The surface should bubble if the malachite is genuine. The reaction time depends on the presence or absence of varnish.
Rice. 1. Determination of the color of malachite trait
Rice. 2. Ammonia test
Do not forget that malachite produced under artificial conditions passes the above-mentioned tests, since it has a similar chemical formula. Unfortunately, there are no methods for determining laboratory stones, so in this case you can only rely on the honesty of the seller.
Results. Verification tests have been proposed to determine the naturalness of a stone.
Conclusions. Buyer awareness of the different types of counterfeit and how to identify it will significantly reduce the number of cases of fraud involving counterfeit malachite.
In terms of its chemical composition, malachite is a fairly simple compound – the basic copper salt of carbonic acid (or the basic anhydrous copper carbonate). Among copper compounds, malachite is one of the most stable minerals, because under the influence of moisture and carbon dioxide, the remaining copper compounds gradually turn into green malachite. Even antique copper or bronze items are often covered with a green coating, consisting mainly of malachite.
Tagil malachite (stone from the collection of the Malachite Box store)
In nature, malachite is formed in the oxidation zone – in the weathering crust of copper ores occurring in limestone or dolomite and calcareous shales. Chemically strong underground waters permeate the copper pyrite, destroy it and take away its copper, combining it with carbonic acid from neighboring limestones.
Dissolved minerals leave pores and voids in the rock, which malachite does not always fill completely and creates a bizarre spongy kidney-shaped surface.
The different shades of green color of malachite depend on the inclusion of other minerals: chrysocolla, asperolite, elite, etc. For example, chrysocolla gives a bluish tint.
The mystery of the birth of the bizarre malachite pattern was studied for a long time by Leningrad professor D.P. Grigoriev. He was especially interested in the process of creating spherulites (buds) with an internal radial-ray structure. In laboratory conditions, D. P. Grigoriev observed under a microscope a crystallization process similar to the origin of malachite. And this is the picture that appeared before his eyes.
. At the uneven edge of the preparation, still small spherulites appeared. As soon as any two adjacent balls, when their rays spread in all directions, come into contact, a platform is formed between them, outwardly similar to that which occurs between balls pressed against each other. From this moment, during the group growth of spherulites, an inexorable mineralogical law comes into force, which determines the fate of each of the spherulites. Through a microscope you can see how the growing spherulites compete for the necessary space and crowd each other out. Some of them freely spread their rays, like a fan, others are limited in growth and sooner or later are caught by their closest neighbors. And, as a result, a crystalline crust is obtained with an internal radiant structure of many centers and an external surface composed of parts of various spheres.
Grigoriev believes that, along with radiance, the successive layers observed in malachite buds depend on fluctuations in the rate of entry of dissolved copper carbon dioxide salt into the cavity of the growing spherulites. Moreover, the rays in them can be so thin that they cannot be distinguished with the naked eye, and then the malachite outwardly appears only layered, concentrically banded, without a radiant structure.
It was from such observations and research that the creation of artificial malachite began. Today, the synthesis of a wonderful green stone has already emerged from the walls of the crystallography laboratory of Leningrad University, and in the Sverdlovsk association “Ural Gems” an industrial installation of artificial malachite is already operating, and the first products have been created from it. Malachite was also synthesized at the All-Union Research Institute of Mineral Raw Materials. Artificial malachite has a uniform density, a green silky shine after polishing, and has no pores or cavities at all.
And yet, in the synthesis of this stone, man is still far behind nature in creative imagination. For natural malachite is much richer than artificial malachite in the variety of green shades and tints, and especially in the intricacy and whimsicality of patterns and designs.
Now let’s talk about the main Ural deposits of malachite. It is in the Urals that the world’s richest deposits of the best decorative green stone are located.
“Excuse me, excuse me,” another reader may say, “what richest deposits of Ural malachite can we talk about today?” Yes, there was once a famous malachite era, grandiose malachite products, world fame. – But that’s in the past. And today everyone says: there is no more malachite in the Urals – there was, but it was all gone.
But let’s listen to what the geologists who studied the Ural malachite deposits say.
For many years, professor of the Sverdlovsk Mining Institute G.N. Vertushkov analyzed and summarized the results of studying the Gumeshevskoye and Mednorudyanskoye deposits. He collected the most complete material about the geological structure of the areas of these deposits, about the history of their discovery, study and development, about the genesis of malachite, etc.
Experts have established that all malachite deposits known in the world belong to a single genetic type and are associated with zones of oxidation of copper ore. G.N. Vertushkov also believes that all Ural deposits are “similar to each other and are confined to the volcanogenic-sedimentary strata of the Tagil-Magnitogorsk trough,” where contact-karst copper deposits developed in the weathering crust.
Gumeshevskoye deposit. For the first time, malachite suitable for artistic products was found in the Gumeshevskoye copper mine. It has not yet been possible to find out exactly when this happened. But in the 60s of the XNUMXth century, Gumeshev malachite was already known.
The mine itself was discovered for the second time (after the ancient miracle) in 1702 by Aramil ore miners Sergei Babin and Kozma Suleya. And the first description of the mine was given by Vasily and Ivan Tomilov: “Up the Chusovaya River, between the Polevye rivers, on a flat pine forest, there are two gumets measuring 55 fathoms in length, 30 fathoms across. And there are holes dug on those gumets. and in those pits there are stones. And there are a lot of izgars around those gumenets that blacksmiths sweep out of their forges.”
At that time, a gentle hill was called Gumenets. This is where the name of the Gumeshevsky mine came from. And the mine itself and its surroundings turned out to be saturated with copper and iron, gold and platinum, marble and malachite. It is not without reason that it was in these places that the legends about the Mistress of the Copper Mountain were born, who personified the wealth and beauty of the Ural mineral resources.
The beginning of the development of the mine is considered to be 1709. Copper ore from it was transported first to the Uktus plant, and then to Yekaterinburg. In 1724, three mines were already operating at the Gumeshevsky mine. The extraction of copper ore was sometimes stopped because it suddenly disappeared, which was explained by the whims of the Mistress of the Copper Mountain.
Tagil malachite (stone from the collection of the Malachite Box store)
In 1759, the Sysert mining plants, together with the Gumeshevsky mine, were sold to A.F. Turchaninov. Under him, obviously, they began to mine malachite for artistic crafts. P. S. Pallas in his “Travels. “gives the following description of Gumeshevsky malachite:
“Behind the coppery clays, the most common superabundant ore lying nearby in the Gumeshevsky mine is hard malachite or hard coppery greens, which are of two kinds: the first type is shelled like the well-known sprouts, which, despite its moderate hardness, is very capable of polishing, and in proportion to the diversity of the overgrown shells the most beautiful colored dark green stripes and waters are visible in it in cut pieces, the most perfect beauty and kindness alone lacking hardness. Such shell-like greens often originate in the vicinity of ferrous and ferruginous grains, and in the crevices of such large and solid piles a fair amount of greenspan is produced, which, however, is very loose.
The other kind is branchy or like fluff from the inside to the outside, separated, dark in color, heavy, richer than the first, on the fluff (apparently on the surface) like velvet, and in the break like satin. Both of these genera lie one next to the other in nests in large and small specimens, which sometimes weigh more than twenty pounds, and in different forms, but most of all in a beautiful likeness to the umbilical bloodstone or in a wavy, disorderly surface with navels, which are most in the first there are some. In shell-like greens it often happens that a stalactic or scale-like arrangement is noticed, which has a well inside along its entire length. On the usually white surfaces shown between the shells, black, extremely large dendritic patterns are visible. »
Actually, from the end of the 18th century, as Bazhov’s grandfather Slyshko said, “our Gumeshki thundered. Their fame spread throughout the whole earth.” And, probably, then the legends were born about the Mistress of the Copper Mountain, whose “dress is made of silk, hear me, malachite. There is such a variety. It’s a stone, but it’s like silk to the eye, even if you stroke it with your hand.”
The Gumeshevsky mine has long been one of the largest in the Urals.
At the end of the 19th century, the mines of the Gumeshevsky mine were filled with underground water, and ore production ceased. True, for many years they continued to process old dumps and even at the beginning of the 20th century they built a special plant for this.
In 1940, an expedition from the USSR Academy of Sciences, led by Academician A.N. Zavaritsky, visited the Gumeshevsky mine and proposed resuming copper ore mining at the mine. This was only possible in 1950, when mining operations resumed and construction of the Kapitalnaya mine began. A new attack on the treasures of the Mistress of the Copper Mountain has begun.
In the Geological Report. “, compiled in 1967 under the leadership of N.N. Senkevich, it is said about the Gumeshevskoye deposit: “Malachite mineralization can be traced. at a distance of about 100 meters and is located mainly in the bottom of the limestone karst depression, under clays containing pieces of brown ironstone.
The depth of malachite mineralization is 70 – 130 m from the surface. Malachite forms copper crusts.”
Professor G.N. Vertushkov also came to the conclusion that malachite at the Gumeshevskoye deposit is still far from being worked out: it remained in old workings and its “primary deposits had not been mined before at all, and geological analysis of the deposit leads to the conclusion about the extremely high probability of their existence.” Therefore, here we need to look for new “malachite cellars”.
However, unfortunately, at present, exploration and mining work in the upper horizons of the Gumeshevskoye deposit, where there may be accumulations of malachite, is complicated by mining operations for the extraction of copper ore, which are carried out at deeper horizons.
Malachite buds (stone from the collection of the Malachite Box store)
Mednorudyanskoe deposit. “This deposit,” wrote A.E. Fersman, “in its power and richness, as well as in the exceptional beauty of the patterns and the purity of the green tones of the stone, is and is still the only one on the entire globe.” It is perhaps more correct to talk about a whole group of deposits that are located near Mount Vysokaya: Korovinsko-Reshetnikovskoye, Vysokogorskoye, Graben and others. But, of course, the most famous of them is Mednorudyanskoye. It was discovered more than a hundred years later than Gumeshevsky.
But they knew about the iron and copper ores of Mount Vysokaya at the end of the 1722th century. And the first plant that was built here was the Vyisky copper smelter (XNUMX).
Tagil malachite was also known back in the 18th century, but its fame began after the discovery of the Mednorudyanskoye deposit, and especially after a unique block was discovered.
Copper mining at Mednorudyanka was carried out very intensively (though with some interruptions) and continues to this day. Malachite was also mined along the way. However, its industrial production is difficult for a number of reasons and has been sporadic in recent decades.
The Mednorudyanskoye deposit is located within the city of Nizhny Tagil, a little more than a kilometer from the Main Quarry of Mount Vysokaya and is confined to the so-called Mednorudyanskoye tuff-sedimentary strata. Among this strata, three main limestone horizons are distinguished, in which there are ore zones with malachite inclusions. Mineralized limestone layers up to 70-80 meters thick have been traced up to one kilometer. Ornamental malachite is common in clays near limestone, slightly below the upper boundary of the cementation zone. Just like in Gumeshki, the malachite here is of the so-called contact-karst origin, but with a more powerful development of karst.
Mednorudyanka malachite occurs in brown iron ore at a depth of 72 meters. There were blocks measuring 6×2 and 8×1,2 meters. Malachite branches up to 37 meters can be traced.
Exploration work in 1961-1962 in the southern part of the Mednorudyanskoye deposit revealed a zone of malachite mineralization.
New reserves of malachite were also discovered at the Korovinsko-Reshetnikovskoye deposit (half a kilometer from Mednorudyanka) and in the Graben section of the Main Pit. But here, too, geologists recommend only incidental mining of malachite.
Despite the objective difficulties for further searches, exploration and production of this green decorative stone, a new malachite era is expected. A group of geologists led by N.N. Senkevich concluded in 1967 that only the Urals were promising for searching for new malachite deposits. (However, in recent years, the Chok-Pak malachite deposit has been discovered in Central Kazakhstan.)
Professor G.N. Vertushkov believes that neither in Gumeshki nor in Mednorudyanka has anyone ever reached the primary deposits of malachite, and geological and mineralogical analysis leads to the conclusion that there is an exceptionally high probability of their existence. In his opinion, the entire area of development of volcanic rocks of the Tagil-Magnitogorsk trough, and primarily the area between Nizhny Tagil and Polevsky, should be considered favorable areas for contact copper deposits. Other areas of the Urals, for example the former Bogoslovsky mountain district, are of no less interest. There should be the same productive malachite deposits as Mednorudyanskoye or Gumeshevskoye.
