Rusty gold coins from the savings bank. Does gold oxidize? The Science of Gold, Rust and Patina

First of all, I decided to go to Sberbank and find out why spots on gold coins appeared, and whether they would accept the coin for purchase.

A large stain near the letter “I”, as well as other stains are visible along the edge of the coin.

The savings bank said that they would accept the coin without questions. not a hindrance, because the Central Bank issued an order in which coins with spots are equated to coins in excellent condition. The main thing is that there are no stains on the coin. Another important thing: At the price of gold, they only buy Pobedonostets and Sochi rectangular ones, the rest are considered not investment. And for my coin of 50 rubles 2015 Sochi Hockey, I was offered 16,500 rubles, which is currently lower than the price of metal in the coin (7.78g * 2600r = 20,228r - the price of metal). Therefore, there is no point in handing it over to the savings bank for purchase.

About the origin stains on gold coins I was told that this was a technological problem.

Theory 1:

I'm happy with my trip to Sberbank. But she continued the investigation. On the Internet I came across a very interesting version, it says that the appearance of such stains on gold coins, may be due to the fact that at the Mint, the stamp with which the coin is minted is not completely cleaned, and that particles of other metals remain on it. These very particles are imprinted into gold coins, and it is precisely these metals that remain on the surface of the gold coin that are oxidized, resulting in stains similar to rust appearing. This theory is quite interesting, I think it has its merits.

In order to be 100% sure and dispel any doubts, I will take this coin to a special laboratory, where they will analyze its composition. In order to make sure of the purity of the metal and that the coin really consists exclusively of 999 fine gold, we submit the coin for examination, where X-ray spectral and fluorescent analysis is carried out on it. This method is used to determine the concentration of elements in substances of various origins. Performs accurate measurements at high speed. It is based on the collection and subsequent analysis of the spectrum that appears when the material under study is irradiated with X-ray radiation. I would like to note that this method of determining precious metals does not destroy or damage the coin. The instrument error is up to 0.5%. Such an analysis is carried out in few places; for those who are interested, it can be carried out at the State Historical Museum for a certain amount of money. So, the analysis showed that the purity of the metal is 24 carats, which is the maximum purity, the gold content is 100%, with an error of 0.3%, that is, the Mint, The Central Bank and Sberbank are not deceiving us, in this case, it is not an impurity or dirty metal, but pure 999-carat gold.

Theory 2:

In the process of our little “investigation,” we talked with one of the managers of one of the largest jewelry factories in Moscow, which produced gold medals of the appropriate standard for the 2014 Olympic Games. He confirmed the formation of orange dots on gold. It was revealed that it was not the metal that was to blame, but the plastic capsules in which these medals were placed. After discovery "rust" on gold, the jewelers took the medals out of the capsules, washed them with a special chemical solution, the stains came off, they packed them back, and after just three days the stains appeared again. In my case, there is no marking on the capsule, the manufacturer is not known, so we cannot exclude the possibility that in stains on gold coins Plastic capsules are to blame. Cleaning the coin, unfortunately, is not possible, since the coin is of PROOF quality and will be hopelessly damaged because it will lose its shine.

However, Sberbank will buy this coin even with stains (for them spots on gold coins not an indicator, since the Central Bank ordered Sberbank to accept coins with these spots), but Sberbank will buy them at the price indicated in their price list, in my case it is 16,500 rubles, but this is not profitable for me, since the price itself There is currently more metal than the price in the Sberbank price list. I found sites on the Internet that buy gold coins at metal prices, so if you urgently need money, it is more profitable to sell a coin there. They also accept gold coins with spots.

The anonymous components of gold alloys determine not only the color of the metal. The durability of the jewelry largely depends on them. It is a myth that gold does not rust. Another thing is that the presence of silver, palladium or platinum in the alloy gives it additional durability. Base metals, on the contrary, make it an order of magnitude more vulnerable.

The most common manifestation of corrosion is the darkening of gold. But there are also more dramatic cases. It happens that wedding rings literally fall apart. By the way, at all times this was considered a bad omen and foreshadowed the inevitable collapse of the marriage. Chains break even more often - especially at the junction points.

Corrosion accelerates noticeably if the product is placed in an unfavorable environment. The active corrosive medium is ordinary human sweat. In addition, red wine is on the “black list”. It has long been noted that this drink is capable of rapidly dissolving the layer of gilding on church bowls. And finally, various detergents. Surfactants, which are certainly present in their composition, can be destructive for any jewelry.

But the main reason for the rapid corrosion of jewelry is technological violations during its production. An arbitrary change in the chemical composition of the alloy, the presence of foreign impurities in it, will almost certainly deprive gold of its durability.

The best samples of the mineral

More articles on the topic:

Nuggets are usually called natural pieces of metal weighing more than 5 - 12 g and measuring more than 4 - 5 mm in diameter. From a geological point of view, gold is an ordinary rare metal, of which there are many in the periodic table. And from the standpoint of common sense, it cannot be compared with such giants as aluminum, nickel, cobalt, and copper.
• Yellow gold jewelry is a hit this season.
Gold is a symbol of the Sun and luxury, the king of metals and the metal of the gods. Its history, covered in countless legends and myths, takes us to the birth of human civilization. Gold, as the most precious metal, has long served as an exchange equivalent in trade, and therefore methods for producing gold-like alloys based on copper arose. Russian gold mining on an industrial scale began its existence in the Urals. Then it started in Kolyma. The first gold discovered by man was most likely found on the surface of the earth. Then the man realized that he could be found by digging and sorting through pebbles in river valleys. Currently, gold is mined mainly from ores, not only gold, but also those in which the main minerals are other non-ferrous metals, in particular copper, zinc, silver, and lead. In this case, they are treated as a fellow traveler. Gold is found in nature both in pure gold ore deposits and in combination with many other geologically related non-ferrous metals. The rarity of gold, despite its unfading beauty, made it a precious metal (precious stones were also selected for the same characteristics). In the first states of Egypt, Mesopotamia, and America, gold relatively quickly became the property of rulers and nobles. Gold is probably the most beautiful of all chemical elements; it has been known to people and valued since ancient times. In nature, gold usually occurs in the form of a metal, and two ways of its concentration are known. The presence of dissolved gold in sea water was established back in 1872; Numerous attempts to develop an economically viable method for extracting gold from sea water have not led to success. Extraction of gold from alluvial sediments using the gravitational method has been known for at least 6,000 years ago. A gold product must have a stamp indicating the metric or carat fineness. Fineness is the amount of pure gold or silver in one gram of metal. If the product bears the mark of one of the Russian assay inspections, you can be relatively calm about its origin. Of course, provided that the brand is real. In Russia, a lot of copper is traditionally added to gold alloys, which gives the gold a pink-reddish hue. But in Scandinavian countries they produce gold that is so pale that the yellowness in it is barely noticeable. The three most famous colors of gold are “red”, “white” and “yellow”. “Red” is our native one, inherited from the Soviet era, and to be more precise, from pre-revolutionary times. Despite all the banality, this rule can be considered universal. The beneficial effects of expensive additives in the form of platinum and palladium on the metal have already been discussed. In addition, the higher the purity of the gold itself, the greater the guarantee that it will retain its marketable appearance over the years. The low mountain range of the Witwatersrand (or simply the Rand) is located in South Africa, in the province of Gauteng. The Witwatersrand is the largest gold deposit in the world - more than 40 thousand tons of the precious metal have already been extracted from its depths.

Does gold rust? You can find out the scientifically based answer. Thank you. and got the best answer

Answer from Egor Akhryapin[guru]
Rust is a metal oxide (or a mixture of oxides). In air, gold does not change its color and does not interact with oxygen even when heated to 400 ° C. Under normal conditions, the surface of gold is covered with a thin adsorbed layer of oxygen, however, even when heated, gold does not combine directly with oxygen, but also with sulfur and selenium. Au2O oxide and Au2O3 oxide can only be obtained indirectly. Conclusion: gold does not rust!

Answer from MAX[guru]
Unless metal also oxidizes over time... Therefore, you can notice that gold becomes dull, does not shine as brightly, etc., etc.

Answer from PASHTET (Pasha888)[guru]
No, because under normal conditions, at an average of 25 degrees Celsius, it does not oxidize like Iron

Answer from AlexChem[expert]
Definitely - gold does not rust! and does NOT oxidize. under normal conditions, as the previous speaker noted.

Answer from Vadim Kotov[guru]
What does it mean to rust? This is what they say only about hardware. Even nickel and cobalt are said to oxidize in air. Copper also oxidizes in air and in some cases, in the presence of moisture, the protecting metal is covered with a noble patina from further oxidation and destruction. Gold practically does not oxidize in air, although indirectly it is possible to obtain reddish oxide and violet gold oxide. In general, with the help of fluorine, gold can be oxidized to its ultimate 8-valence state. Recently, a 7-valence gold compound was obtained for the oxidation of some difficult-to-fluorinated compounds with fluorine. In general, with the help of photonuclear reactions occurring inside the melt with the help of an arc burning inside the melt, for example, inside iron, it is possible to obtain gold through lanthanide compression, but it is better to use tin, lead, and mercury for this purpose. This problem was dealt with by the little-known professor Bolotov back in the Union.

Answer from Dmitry D.[guru]
What the hell oxidizes if gold occurs in nature in the form of nuggets or gold sand. What do you think miners are mining? It lies there for millions of years - and nothing!

Answer from VD[master]
Gold does not “rust” because it does not interact with oxygen. A does not interact with oxygen, because the valence electrons occupy states in it that are more favorable in terms of energy than if they went to oxygen. But in hardware it’s the other way around. So it's all about the electronic structure.

Answer from Alekx KU[guru]
a chemically inactive, stable precious metal, like all metals, has the property of oxidizing (rust oxide) in order to oxidize it requires a condition, in the natural environment (conditions) oxidation, as well as oxide reduction, does not occur; energetically unfavorable processes (balanced) enthalpy does not change so much that there was a shift (direction) of the process

A selection of materials for those who are interested in the topic:the appearance of "rust" on gold coins !
Source - http://wzascok.livejournal.com/6505.html

As a former chemist, this topic also turned out to be interesting to me, especially since at one time I inherited a rather impressive collection of coins.
True, I have never seen rusty gold coins with my own eyes, although there are quite a few of them, maybe gold was different before? ... at least I've never met a rusty oneNicholas gold chervonets, and rusty gold Finnish markstimes of the Russian Empire...
Well, in general, read, draw conclusions, my opinion is thatthe reason still lies both in the stamp itself and in the coin stamping technology.

21.02.11/18:31

Recently, information about “rusty” gold coins “St. George the Victorious” has periodically begun to appear. Sometimes they say that a patina has appeared on the “St. George the Victorious” coins. Entrepreneur German Sterligov was the first to report this phenomenon several months ago. He published photographs of coins that clearly showed stains that were a different color than the coin. FinNews.ru decided to look into this problem and found out the following.
Do "rusty" coins exist?

Only a few of the banks surveyed admitted that their clients were faced with the problem of “rusty” coins. The press service of Sberbank of Russia reported: “There were cases when “Victorians”, which most often have red spots and/or stripes on coins, were brought back to Sberbank for a return purchase, but they were returned not because of the spots, but just like coins." The press service of North-West Sberbank said: “Yes, such coins do exist.” The press service of the Khanty-Mansiysk Bank reported: “In one of the branches, the client kept them in a safe deposit box. He came to pick them up, and they had “rusty” stripes on them.”

Other banks (including those playing a significant role in the precious metals market) either denied the presence of such problematic coins with their clients, or ignored questions from FinNews.ru. Since the largest player in the precious metals market (Sberbank) admitted the existence of a problem, the silence or denial of such a problem by other banks indicates either the insignificance of their real role in the precious metals market (there are not many “rusty” coins, so they have not yet come across such coins ), or about trying to bury your head in the sand.

What do the bankers say?

Some banks have made "everyday" assumptions about the reasons for the appearance of "rust" on gold coins. Thus, SMP Bank suggested that “This is a “patina”, it appears after 5 years of storage, like on jewelry with a long shelf life. They clean it, like jewelry, with a special composition.” The North-Western branch of Ak Bars Bank suggested that “Rust is oxides of gold (chemically pure) from contact with hands that are not perfectly clean. Sweat contains a lot of urea. A lot of things can end up on our hands after we have touched everything around yourself, brushed your teeth with fluoride paste, or touched mercury-containing batteries. There are a lot of cases." Elena Novikova, head of the department of plastic cards, commission, savings and investment products at Absolut Bank, said: “It is not recommended to touch the coin with your hands, since the fingerprint left on its surface (especially on the mirror field) is practically impossible to remove. Even in If the trace is successfully cleaned, it is possible that fatty residues invisible at first glance will enter into a chemical reaction with the composition of the coin’s surface and later oxidation spots will appear in this place.” The cash circulation department of the Bank of Russia stated that “in some cases, depending on the storage conditions, spots may appear on them, which are metal oxides and microscopic particles of various substances falling on the surface of the coins. The presence of spots does not characterize the coins as defective.”

To understand how true these assumptions are, it is necessary to brush up on your chemistry knowledge. Those who studied well at school and/or college may not read the next chapter. For the “victims of Fursenko” we will report the following.

The Science of Gold, Rust and Patina

The same department of cash circulation of the Bank of Russia reported that “The gold coin with a face value of 50 rubles “St. George the Victorious” is a coin of investment value, the mass of the precious metal in purity is 7.78 grams, the gold purity is 999.” 999 purity means that one kilogram of coins will contain 999 grams of gold and only 1 gram of other metal impurities (usually silver and copper). What does science say about the physical and chemical properties of gold?

Pure gold is a soft yellow metal. Gold is very malleable and malleable (for example, from a piece of gold weighing one gram you can stretch a wire three kilometers long or make gold foil 500 times thinner than a human hair - 0.1 microns). The softness of pure gold is so great that it can be scratched with a fingernail.

Gold is the most inert metal, standing in the series of stresses to the right of all other metals, under normal conditions it does not react with most acids and does not form oxides(emphasized by the editor), due to which it was classified as a noble metal, in contrast to ordinary metals, which are easily destroyed by the environment. Gold dissolves from pure acids only(emphasis added) in hot concentrated selenic acid: 2Au + 6H2SeO4 = Au2(SeO4)3 + 3H2SeO3 + 3H2O. In aqueous solutions of cyanides with access to oxygen, gold dissolves, forming cyanoaurates: 4Au + 8CN− + 2H2O + O2 → 4− + 4 OH−. Gold reacts with dry chlorine at ~200°C to form gold(III) chloride. In a concentrated aqueous solution of hydrochloric and nitric acids (regia vodka), gold dissolves to form chloraurate ion already at room temperature: 2Au + 3Cl2 + 2Cl− → 2−. Gold easily reacts with liquid bromine and its solutions in water and organic solvents, giving tribromide AuBr3. Gold reacts with fluorine in the temperature range 300−400°C; at lower temperatures the reaction does not occur. Gold also dissolves in mercury, effectively forming a low-melting alloy (amalgam). There are organogold compounds (for example, diethylgold bromide). All alloys above 750 fineness do not tarnish in air (that is, they are not covered with a thin film of oxides, editor's note).

What is rust? Rust is a common name for the result of the corrosion process of various metals. Corrosion (from the Latin corrosio - corrosion) is the spontaneous destruction of metals as a result of chemical or physico-chemical interaction with the environment. From a chemical point of view, rusting, for example, of iron is oxygen corrosion of iron in water: 4Fe + 6H2O + 3O2 = 4Fe(OH)3. Hydrated iron oxide Fe(OH)3 is what is commonly called rust.

From the Great Soviet Encyclopedia it is known that patina (Italian patina) is a film of various shades (from green to brown) formed on the surface of products made of copper, bronze and brass as a result of metal corrosion under the influence of the natural environment or as a result of patination, that is, heating or treatment with oxidizing agents.

Domestic causes of rust are excluded

So, since the gold coins “St. George the Victorious” have a purity of 999, they should neither tarnish nor rust. Toothpaste containing fluoride compounds cannot damage the coin in any way. Exactly the same as urea. Cyanide compounds, as well as mercury and bromine, do not come into contact with humans in ordinary life. Traces of secretions from the skin's sweat and sebaceous glands can be easily cleaned with organic solvents, which will dissolve fat and wash away inorganic compounds, but the solvents will not interact with gold in any way.

The term “patina” does not apply to St. George coins, since they are made of gold, not copper. German Sterligov also spoke about this in one of his speeches: “I sent [the “St. George the Victorious” coin, editor’s note] for examination to the Institute of Steel and Alloys, and there the professors explained with a smile that patina and gold are two incompatible things. If there is gold, then there cannot be a patina. If there is a patina, then it is not gold."

There is no doubt that the coin is made of 999 fine gold. If this were not so, it would have become known long ago. The fact is that “St. George the Victorious” coins have been used by jewelers in the production of jewelry since the very beginning of their sale in 2006 due to the absence of VAT in the price of such coins, as well as the high purity of the metal in these coins.

There is a contradiction - there shouldn’t be rust, but there is. Let us return once again to the commentary of the cash circulation department of the Bank of Russia: “In some cases, depending on the storage conditions, stains may appear on them, which are metal oxides and microscopic particles of various substances falling on the surface of the coins.” This comment is akin to saying that Newton explained why the apple fell, but did not explain how it ended up on the tree. So it is here - the Bank of Russia explained that rust appears due to microscopic particles, but did not explain how they appear on a coin stored in a plastic capsule in a bank safe.

What's really going on?

Fortunately, the world is not without good people. Representatives of the two banks quite logically explained the origin of the “rust” on gold coins.

Stanislav Filippov, head of the financial markets operations department at Rus-Bank, said the following: “As for the defects themselves, it must be said that this problem is not new. Periodically, individual batches of coins appear on the surface of which after 2-3 years (depending on conditions) storage) various cloudings, changes in color or reflective properties appear. All of these changes are nothing more than a manufacturing defect, and a superficial one at that. The reasons for its appearance most likely lie in the ingress of foreign chemical impurities onto the surface of the stamp, possibly during its cleaning, although "Probably only mint technologists could provide more detailed information."

Azat Salyakhutdinov, head of the precious metals department at Ak Bars Bank, said the following: “Rusty” coins and bars appear due to the presence of microscopic particles of iron on their surface, which are transferred there upon contact with an iron tool during the manufacture of a coin or bar. Typically this occurs during stamping or rolling. Rust is much larger in volume than the piece of iron that gave birth to it (about 300 times), so what is invisible in the form of microscopic pieces of iron becomes visible in the form of rust after storage in a relatively damp room (sometimes the moisture that gets into the capsule along with air). Iron was transferred to coins during the rolling of sheets, during the manufacture of blanks for coins; in connection with the identified cases, an investigation was carried out at the mints, which determined the origin of the defect. Now, as far as we know, this has been eliminated in production, and the MRH carries out strict visual control of all coins sold. There are also such spots on ingots, but only on stamped ones and, as a rule, made on worn dies. Dies for gold coins are coated with gold, so rust cannot appear during this process, but at the refinery they treat this a little more easily.”

How to prevent coins from rusting?

Elena Novikova recommends “Store coins in a dry place without sudden changes in light and temperature. To remove a coin from a capsule if necessary, for example, for weighing it or for detailed inspection, there are special gloves or tweezers with soft tips. You can also purchase a special dust blower, chemical stain removers, storage boxes and capsules and other accessories for working with coins." However, as we have already found out above, gold is very inert, and ordinary light and temperature conditions do not affect it in any way. But the requirement for a dry room in the light of the above acquires key importance.

The press service of the Khanty-Mansiysk Bank recommends “Store at the required humidity and temperature,” without specifying the required humidity and temperature values. In addition, the bank itself admitted that a safe deposit box is not a place where the humidity and temperature necessary to prevent the appearance of traces of “rust” on coins are maintained.

It is obvious that the bankers' answers are affected by the obvious insufficiency of the knowledge they received at school in the natural sciences. Against this background, the so-called reforms of school education, carried out by the relevant ministry under the leadership of citizen Fursenko, will only lead to an even greater deterioration (albeit much worse) of the general level of education of the Russian population. Reforms, and, in fact, the destruction and degradation of school education must be stopped immediately.

But we digress. So, if a microscopic particle of iron appears on the surface of a gold coin due to a manufacturing defect, then it is not possible to prevent the “rusting” of such a coin. Rusting of iron is inevitable, because there is always water vapor and oxygen in the air, which cause corrosion.

What to do with "rusty" coins?

Bankers are unanimous in their opinion - there is no reason to panic.

Azat Salyakhutdinov believes that “There is really nothing wrong with these stains, they are superficial in nature, can be easily removed with simple chemicals, and have virtually no effect on the test quality.”

Stanislav Filippov believes that “Owners of coins on the surface of which the indicated defects have appeared, first of all, should not panic and get rid of such coins at any cost. If they were purchased from a bank with a good business reputation that has been operating in the financial market for a long time, then there is no doubt about their There is no authenticity. In any case, the value of such coins cannot be lower than the value of the gold they contain. The buyer of the coins can only ask for a slight discount for appearance.

You should not change your preferences when choosing investment funds. Ordinary people who do not have the opportunity to store precious metals and products made from them in favorable conditions can be recommended to invest in gold through impersonal metal accounts. Gold on compulsory medical insurance is not accessible to thieves and will never “rust”!”

North-West Sberbank, when detecting “rusty” gold coins in cash centers, rejects them and sells them at a reduced price to UO/VSP clients through the branch network.

VTB24 press secretary for the Northwestern Federal District Ivan Makarov invites owners of “rusty” gold coins to “make a claim about the quality of the coins to both the selling bank and the coin manufacturer.”

So, let's draw conclusions. The problem really exists. There are shortcomings in the production technology of gold coins and bars made by stamping, due to which the smallest particles of iron appear on the surface of some coins, invisible to the naked eye. Over time, these iron particles corrode and the corrosion products become visible to the naked eye. The defect is superficial and only worsens the appearance of the coin, without affecting its essence as a means of saving capital. If one or more of your coins have rust stains, there is no need to try to get rid of them immediately. The difference in price compared to a coin without rust is 50-200 rubles or approximately 0.5-2.0% of the coin’s price.

Why is the Bank of Russia “silent”?
Speaking of the manufacturer. In the case of “rusty” gold coins, the only thing that defies reasonable explanation is the position of the Bank of Russia. The coin issuer is completely indifferent to its reputation and the reputation of its product. We found out that the “rust” on the coin is the result of a manufacturing defect. That is, there are defective gold coins in circulation. It has long been accepted all over the world that defective goods are replaced free of charge at the expense of the manufacturer. But the Bank of Russia does not react in any way to the current situation. It's been at least six months now. Not only that, according to Stanislav Filippov, the Bank of Russia does not buy coins back, and Russian banks do not have the opportunity to replace defective coins. So, the issues of repurchase of coins from the population by credit institutions are not regulated in any way by the Bank of Russia. This is what the regulator’s cash circulation department reported. Why doesn’t the Bank of Russia replace its defective coins? And when will he start doing this? Or can only a court decision in a case on consumer protection be able to force the Bank of Russia to fulfill its duties properly?