Hello, dear gold lovers! Many people admire its pleasant shine, although not everyone knows that it is due to the structure of its energy levels and the highest number of electrons among metals. Every woman wants to feel the pleasant weight of a massive precious necklace on her neck, not realizing that the reason for the large weight of gold jewelry is the high density of gold. Read this article - and you can easily figure out what this value means and what practical significance it has.
Natural qualities and composition
If we take into account pure gold, which has no impurities, then it is a metal of increased softness, with a characteristic yellow color. Softness can be determined on a ten-point Mohs scale; according to this scale, the hardest is diamond, the hardness of which is measured at 10 points (as you know, diamond can be used to cut glass). If we compare it with gold, then its density on the Mohs scale is 2.5 - 3 points. Speaking about the density of 585 gold, suffice it to say that it can be scratched simply by running a fingernail over it, and if you apply some effort, it can be cut without much difficulty with a knife.
Comparative table of densities of metals mined in nature
Thermal conductivity is high, resistance is low. It should be noted its special malleability, as well as its ductility. It is the ductility that distinguishes gold leaf, the sheets of which are unusually thin; the composition of such a material is truly unique. It is noteworthy that in order to stretch a wire 3 km long, only 1 g of gold is enough. Polishing is also very easy, it should also be noted that it is highly reflective. It is this quality that is very important not only in jewelry, but also in many other industrial fields.
As for gold miners, the most important quality for them is density. It should be noted that only metals belonging to the platinum group have a higher density.
- The density of this metal is 19,300 kg/cubic meter. To make it clear, it must be explained that one of the most expensive metals in the world weighs 19.3 times more than water.
- If a liter bottle is filled with gold sand, its weight will be approximately 16 kg.
- 1 kg can be represented by a cube with a side of 37.7 mm or it can be represented as a sphere whose diameter is 46.2 mm.
How to distinguish real yellow metal from a fake
Understanding the essence of density as a physical quantity will help us distinguish real gold from counterfeit gold. I'll tell you how to do this.
Au has virtually the highest density of any precious metal other than platinum, meaning that almost any gold item will weigh more than a gram.
The easiest way is to weigh the jewelry. The method is suitable for small openwork decorations.
Massive rings and chains, bracelets and earrings are checked based on the ratio of mass to volume.
We will need:
- precise scales with divisions down to a hundredth of a gram,
- beaker with volume graduation. The narrower it is, the higher the accuracy of the determined value. It can be purchased at chemical stores and sometimes in pharmacies.
For clarity, I will try to determine the authenticity (maybe the purity) of my rose gold bracelet:
- I weigh the bracelet on the scales. It weighs 4.62 grams.
- I pour water into a beaker and put the bracelet in it. The water should completely cover the decoration. The bracelet displaced 0.4 centimeters of cubic water. That is, I have a beaker with a CD of 0.1 cm3, the water level has risen by 4 divisions.
- I make the calculation: 4.62/0.4=11.55.
- I compare the obtained value with the table of metal densities and the table of Au density (depending on the sample).
Palladium is close to the obtained values - 12.2, lead - 11.34, silver - 10.49. But my bracelet is a nice shade of pink, which means it most likely contains gold and copper. From the table we see that the density of my bracelet corresponds to 375 samples - the average value of gold, silver, palladium and copper.
The amount of pure element in the alloy is determined using the molar mass of gold using the formula M = m/n. The molar mass of Au is 196.9665 g/mol. In my bracelet weighing 4.62 g and 375 samples, there is 4.63 * 0.375 = 1.74 g of gold, 1.74 g / 196.9665 g / mol = 0.001 mol of pure gold.
Gemini of gold
It happens that unscrupulous jewelers, knowing that the density of the yellow metal or its alloys is close in value to base metals, use this value for criminal purposes. Thus, lead with gold plating can easily pass for 375 standard, and tungsten, which has a molar mass close to platinum group metals, is often passed off by jewelers as precious metals.
About notable properties
If you take an ordinary glass and fill it halfway with gold, its weight will be 1 kg. But as for the native version, its density is lower than that of the chemically pure one, here the indicators range from 18 to 18.5 g/cc. The weight of 585 gold is even lighter, since its density is lower, this is explained by the fact that we are talking about an alloy here. But as for 999 gold, the density here is higher, so when talking about density, the sample is of great importance. It is the composition of the 999 sample that does not have any impurities, which is why its cost is one of the highest. If we talk about the composition of 585 sample, then there is silver, copper, nickel and palladium. Thanks to its unique qualities, this option is the most popular in the jewelry industry. As for the 375 standard, the composition includes copper and silver, this option has a significant disadvantage - it darkens quite quickly.
It should be noted that it is precisely such an indicator as the high density of gold that is the main factor that contributes to its relatively easy extraction. Even the simplest technological processes (for example, washing at sluices) can provide a very high degree of recovery from rocks.
It is noteworthy that if large volumes are not expected, then grinding can be carried out independently; no expensive equipment is required for this, an ordinary washing tray is sufficient. This method of extraction has been widely used since ancient times. When there was the famous “gold rush” in California and the Klondike, grinding was also actively used there. People have long understood that it is thanks to high density that they can easily obtain what is highly valued. And there are no prerequisites for its value to decrease.
Relationship between density and fineness of gold
The density of the 999 sample is closest to the number 19.3 g/cm². Therefore, if you do not know the sample of your product, you can determine it by density. This method will differ from the chemical one and using a jeweler. But nevertheless, it can be done even at home.
So, since all other metals are less dense, their impurities in gold make the final alloy less dense. If you have 585 red gold, it means that copper has been added to it, and the density of the product has decreased. Impurities from nickel and zinc will also reduce this indicator. Only palladium and platinum will increase the density of the ring.
Therefore, to determine a sample using density at home, you need to take a test tube or beaker. Next, measure the water levels before and after lowering the gold jewelry into the test tube. Weighing in water is an old method that was used even before the revolution. It gives a measurement error of approximately 20–30%.
The chemical properties of gold are an important indicator that influences the cost and indicates that the precious metal was not in vain chosen as luxurious and expensive. Perhaps these properties will be used more often in the future. But at the moment they are used only in a few areas of life.
Helpful information
The fact is that if you wash the yellow metal with a stream of water, you can get rid of minerals that have a lower density (and almost all minerals found in the earth’s crust have a lower density). After intensive washing, they are washed off, after which the metal itself is concentrated in the heavy fraction, which is sand consisting of minerals of high density, this is called concentrate. After which the concentrate should be washed to look for any jewelry that has settled in it.
If we talk about modern times, the mining method, which is based on the high density of the metal, has found wide application for extreme tourism. Such tourism in most cases is organized by the owners of private mines, which have already been developed and are economically unprofitable. For a fee, tourists can be taught simple mining techniques. Of course, you should not expect that you can get a troy ounce in this way, but delight is undoubtedly guaranteed. Who doesn't want to feel like a real gold miner! For such reasons, tourism of this type is one of the most popular.
If we talk about comparing the densities of gold and silver, the latter metal has a density of 10,500 kg/cubic meter. m. But the density of tungsten is very high, it is almost comparable to the density of one of the most expensive metals and is no more than 1% inferior to it. These are the reasons why the value of gold and silver is very high all over the world. Of course, silver is significantly inferior in this regard. The composition here also varies - the fact is that pure silver is used very rarely. This is explained by the fact that in its pure form it has increased softness, which creates certain difficulties. If we are talking about 925 silver, this means that its composition should include no more than 7.5% of various types of impurities. 925 silver contains platinum, and may also contain zinc, germanium and often silicon. In this way, you can make silver not only less soft, but also affect the change in its color. And the physical properties also change for the better, for example, it is less susceptible to oxidation.
This kind of silver is one of the most common in the jewelry industry because it has an attractive appearance and unique physical properties. It was used in England for minting coins, which is a very important indicator.
If we compare with 960 standard, then, undoubtedly, products made from such metal are very sophisticated, but they are not particularly durable. Therefore, it is not possible to use it for everyday wear. Such jewelry can only be worn on special occasions, and the beauty of products of this type can cause true delight among all connoisseurs of beauty.
Industries using alloys
Platinum has a wide range of applications, but the main one is the jewelry industry
Platinum material is indispensable in the chemical and instrument-making industries. It is used in the aviation industry. But the main consumer of platinum and high-grade alloy based on it is the jewelry industry.
From the first quarter of the 19th century. the chemical element was used as an alloying component for the production of high quality steel. Before the invention of liquid crystal displays, screen coatings were made with a platinum compound.
In the 70s last century, platinum was used in automobile production. And currently, one of the main consumers is this industry, where the metal is used as a catalyst for cleaning exhaust gases from harmful compounds.
The device is a cylinder with an elliptical or circular cross-section, inside which there is a kind of honeycomb made of metal or ceramic, coated with a solution of platinum group metals.
In electrical engineering designed for low currents, alloys of the chemical element with gold and silver are used. The physical property of platinum, the ability to magnetize, is used in the manufacture of alloys of magnetic materials in the production of small-sized electrical appliances.
The material is used to make electrical parts and devices designed to operate in special conditions and aggressive environments:
- reactors;
- high-temperature furnaces (crucibles);
- thermocouples;
- for coating reactor surfaces;
- electric heaters;
- mirrors for laser technology;
- equipment for the production of optical glass.
Platinum-coated devices make it possible to obtain chemically pure preparations or products in the food industry.
Platinum group metals are used to make various laboratory instruments and equipment. They are used to produce utensils for melting alkalis, bowls for working with acids, boilers, and autoclaves.
Special needles are made from an alloy of gold, platinum and palladium; soldering on fountain pen nibs is made from it. Platinum is used in medicine as an element that slows down the development of disease.
Use of magnetism
Gold also differs from other metals in its magnetic permeability. This precious metal is diamagnetic (it is repelled by a magnet) in contrast to tungsten, which is paramagnetic (it can be attracted by a magnet). Therefore, when a magnet is applied to pure gold items, they should slightly repel. To increase the accuracy of determining the authenticity of gold in coins using this method, you can use special magnetic scales. They will reliably show the repulsive or attractive magnetic properties of an object. Typically, such measuring instruments are accompanied by tabular values corresponding to certain gold coins and bars. This research method is quite applicable even to bullion gold in a special shell.
Density of gold in coins
The specific gravity of gold, or its density, is considered one of the highest. A gold cube with a side of 10 millimeters has a mass of 19.3 grams. It follows that if we know the declared dimensions and weight of a gold coin or bar, then determining the authenticity of the gold will not be difficult. The characteristics of precious metal products can always be found on the manufacturer’s website. For further independent examination, we will only need precise measuring instruments. This can be a universal Fisch tester, which immediately determines geometric and weight parameters, or separate jewelry scales and calipers. You can also measure the density of gold in a coin using Archimedes' law.
But if a gold coin has a purity of less than 24 carats, then the listed tools and techniques will not be enough, since attackers can use impurities with a specific gravity close to gold in their counterfeits. To do this, counterfeiters often use tungsten, whose density is 19.25 grams per cubic centimeter. By covering this metal with a thin gold plating, it is possible to produce fakes with the characteristics of the American Eagle or Krugerrand, which have a purity of 916.
Because of the CertiPack type packaging, in which, in addition to the bar itself, a certificate with a serial number and the name of the mint is also supplied. With bars in such packaging the situation is different. It is not possible to measure the mass of gold, since it can only be weighed in packaged form. The manufacturers also did not bother to indicate the weight of the metal along with the packaging material. In this case, the authenticity of the product can be assessed only by the dimensions, information about which is in the public domain.
Platinum in monetary production and jewelry
Bank ingots are formed from chemically pure noble metal, which is allowed to contain natural impurities. They are intended for the following purposes:
- transactions at the interbank level;
- technical application;
- production of chemical compounds;
- production of semi-finished products and alloys for various industries.
Along with silver and gold, commemorative and commemorative coins are minted from platinum. It is used to make commemorative insignia for merit.
Platinum occupies a special place in jewelry. Every year the industry consumes about 50 tons of precious metal. The design of jewelry and the alloys of materials used to make them depend entirely on fashion trends.
Recently, the market has been filled with white gold jewelry, which in turn increases the demand for platinum and its group of metals. Finished products made from a gold alloy with alloy additives are eventually coated with a metal from the platinum group - palladium.
The cost of platinum in products is relatively high. But only the platinum base creates a unique play of diamonds in jewelry. Such jewelry is distinguished by its strength, durability, resistance to deformation and mechanical stress.
