Silver is the most common precious metal. It is white in color and has fairly high ductility, making it easy to forge. It has reflective qualities, which makes it in demand in industry for the production of reflective surfaces. The density of silver in its pure form is 10.5 g per cubic centimeter. It is very resistant to corrosion.
Being in nature
Silver is 65th in abundance among the elements found in the earth's crust. It is the most common of precious metals. The silver content in the earth's crust is approximately 0.075 g per ton of rock. This figure is 20 times greater when compared with gold or platinum. Silver is found in different quantities in different places. Typically this value varies between 0.05−1 grams per ton.
But various geological processes can also occur that increase the concentration of white metal to 1 kg per ton of rock. For example, there is a deposit called “Goltsovoye”. It is located in the Magadan region. In this mine, the concentration of silver reaches 1.2 kg per ton.
The precious metal can also be found in sea water, where its amount is an order of magnitude higher than gold. On average, this value is 0.00004 g per cubic meter.
The chemical activity of the material makes it quite difficult to find in its pure form. But there have been cases in history when people found truly huge nuggets. In 1894, the largest piece of silver was found in Colorado, which weighed 1065 kg. After melting, it was possible to obtain 835 kg of pure substance. Today it would be worth more than half a million US dollars.
There are almost 60 minerals in nature that contain silver. Often this element is included in sulfide ores of zinc, antimony, bismuth, copper and lead. Also, metal is always present in gold ores.
Indicators of the specific gravity of other metals
Specific gravity is an indicator that is an integral characteristic of other metals.
The specific gravity of silver is affected by the fineness of the alloy. When other metals (copper, nickel) are added to it, the specific gravity and density are lost. Thus, the density of copper is 8.93 g/cm3, nickel – 8.91 g/cm3. All values are calculated using formulas.
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Silver is the same noble metal as gold. Its specific gravity is 10.5 g/cm3. It melts at a temperature of 960 degrees. The main physical characteristics of silver are:
- corrosion resistance;
- low resistance;
- increased light reflectivity.
Despite its natural softness, silver has a high density and specific gravity.
Titanium is a non-ferrous metal of a white-silver hue. It has high strength, although it is light in weight. So, it is 12 times stronger than aluminum and 4 times stronger than copper and iron. In terms of the degree of presence in the earth's crust, titanium is given fourth place among the rest.
The low specific gravity of titanium - 4.505 g/cm3 is more consistent with alkali metals. An oxide film forms on its surface, which prevents the formation of corrosion.
Zinc is also a non-ferrous metal with a white-bluish tint. It has medium hardness and an initial melting point of 419 degrees. Under the influence of a temperature of 913 degrees, this metal acquires a vaporous state. Zinc has a specific gravity of 7.13 g/cm3.
Normal temperature makes zinc brittle, but increasing it to 100 degrees makes the metal flexible and ductile. When interacting with air, an oxide film forms on the surface of zinc.
The color of lead is dirty gray, but this does not affect the natural shine of the metal. However, the glow stops quite quickly due to the formation of an oxide film on the surface of the lead. The lead alloy has a high specific gravity - 11.337 g/cm3. In this indicator, it exceeds zinc, aluminum, iron and some other metals. Despite its high density, lead is a very soft metal.
It is easy to knead in your hands or scratch with your nails. For lead, a temperature of 327.5 degrees is enough for it to begin to melt.
The table shows the specific gravity and melting points of other metals.
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| Name of metal | Melting point, °C | Specific gravity, g/cc |
| Zinc | 419.5 | 7.13 |
| Aluminum | 659 | 2.69808 |
| Lead | 327.4 | 11.337 |
| Tin | 231.9 | 7.29 |
| Copper | 1083 | 8.96 |
| Titanium | 1668 | 4.505 |
| Nickel | 1455 | 8.91 |
| Magnesium | 650 | 1.74 |
| Vanadium | 1900 | 6.11 |
| Tungsten | 3422 | 19.3 |
| Chromium | 1765 | 7.19 |
| Molybdenum | 2622 | 10.22 |
| Silver | 1000 | 10.5 |
| Tantalum | 3269 | 16.65 |
| Iron | 1535 | 7.85 |
| Gold | 1095 | 19.32 |
| Platinum | 1760 | 21.45 |
World deposits
Silver is mined from fundamentally different types of deposits. There are only two such types. They are divided as follows:
- Directly silver deposits. If you process all the mined ore, then more than 50% of the cost of all elements will be allocated to silver.
- Deposits where polymetallic ores are mined. The extracted rock contains several metals at once. Among them, silver accounts for no more than 15% of the total final price.
The world receives only 25% of silver from the first type of deposits. The rest is mined from polymetallic rocks. In them, the production of this precious metal is a by-product. Such ores include:
- nickel;
- copper;
- gold;
- cobalt;
- lead-zinc.
All silver production processes associated with mining, processing and isolation are very similar to gold. After the ore is extracted and prepared, a concentrate is produced using cyanidation. Pure metal comes out of refineries.
Mexico remains the leader in silver mining. Then comes China, which continues to increase production every year.
Physical properties of silver
The density of 925 is 10.36 g/cm3, that is, the density of silver in kg per m3 is 10360. This metal is quite difficult to melt and is very ductile. From 1 kg you can make a wire whose length will be 2 km. When exposed to oxygen, the metal does not oxidize, which is why it is considered noble. But it reacts with iodine and sulfur, which is why a dark film gradually appears on the surface, so jewelry must be constantly looked after.
Metal is very easy to process. It can be easily rolled out, drawn out, polished and cut. Jewelers like these qualities, but they negatively affect the longevity of the product. It is not used in its pure form, but is alloyed with copper.
Sterling silver is 925. It is almost pure with very little copper added. It is used in jewelry and for the production of tableware.
In its pure form it is a very heavy metal. The specific gravity of 925 silver is 107.87 a. e.m. It is a superconductor of electricity and heat. Basic properties:
- It has the lowest melting point when compared with other precious metals.
- Dissolves only in mercury, nitric and sulfuric acid.
- Does not react with substances.
- It cannot be dissolved in aqua regia.
Composition of 585 gold
First you need to understand that the sample of gold determines its density. In other words, how much pure gold is in the product itself?
Any decoration has two components:
- the metal being tested (directly the content of gold itself in the product);
- alloy metals (various impurities that help give the product strength and the required color in the output).
It is important to remember that, by its natural properties, gold is a very soft metal, so in itself it is unsuitable for the invention of jewelry.
Jewelry 585
What does the composition of 585 gold look like:
- Pure gold (58.5%).
- Copper (33.5%).
- Silver (8%).
It is this composition that allows the product to be durable and beautiful at the same time. Moreover, this composition provides a color familiar to our eyes with a reddish warm tint. If it is necessary to obtain a cooler color, it is necessary to use more silver in the alloy. Knowing these nuances, you can determine by eye which alloy metal predominates in the alloy.
How can one determine the specific gravity of gold? This precious metal is quite heavy and its specific gravity is expressed in g/cm3. So the specific gravity of gold is 19.3 g/cm3. In fact, the specific gravity indicator is equal to the density of the metal. This is why the specific gravity of gold and silver, for example, will be different, since the density of these metals is different. The density of metals itself is different. For example, the specific gravity of gold and lead will vary significantly, since the weight of lead is 11.336 g/cm3. Lead, in principle, is not a precious metal, so calculating its density is unlikely to be of interest to jewelry lovers.
Alloys and samples
An alloy is a mixture of pure silver and some other metals. This is done to improve the required characteristics. Each state regulates the permitted amount of impurities and their types for each sample.
Features of various alloys:
- 960 sample. Almost pure metal. Used for filigree work.
- 925 sample. It is often used in jewelry.
- 875 sample. Not a very popular alloy among jewelers, as it has a yellow tint.
- 830 sample. Used in industry.
- 800 sample. Used in the production of cutlery. This alloy oxidizes quickly.
Ingots are also made from silver, since it is a currency metal. These bars are sold in banks. For production, pigs weighing 20 kg are made. In some cases, you can also find a round shape. These ingots have the highest purity of all at 99.9%. The standard denomination of the product is 5 US dollars.
Specific gravity of 999 gold
This sample is recognized as the purest from an economic point of view and is actively used by banks to provide investment opportunities. The 999 sample got its name due to the density of gold in the alloy, which is 99.9%. It is easy to guess that the specific gravity of gold in such an alloy will be equal to 99.9% of the weight of the entire product.
999 gold bars
However, most often the 999 standard can be found exclusively in the form of bank bars. This is due to the fact that 999 standard is not suitable for making jewelry, as it is too difficult to work with. The fact that this alloy contains practically no impurities makes the work of jewelers almost impossible.
At the same time, it is easy to trace the pattern: the standard of gold expresses precisely its weight. For example, in a 750-carat product, the density of pure gold is 75%. For example, if we imagine a gold bar weighing one kilogram, we understand that it will consist of 750 grams of pure gold and 250 grams of alloy metals.
As mentioned above, the density of metals is different. However, there are indicators very close to each other. For example, the specific gravity of tungsten and gold is almost the same. This is why tungsten, with a density of 19.129 g/cm3, is very attractive to counterfeiters.
Today, masters of modern alchemy do not strive to obtain gold metal from mercury, but actively use tungsten to make counterfeits. A metal such as tungsten can be used to create ingots, the composition of which can only be determined by an experienced person. In order to avoid unpleasant situations, purchase jewelry from certified stores that provide quality guarantees, seal all products and put the appropriate hallmark on them.
Application in jewelry
The metal lends itself perfectly to any processing carried out in jewelry. This determines its great popularity in the manufacture of various jewelry.
The biggest disadvantage of pure metal is that it tarnishes after a certain time, which necessitates cleaning. This issue is resolved with the help of rhodium. The finished product is covered with a thin layer of this material. It helps protect jewelry from various mechanical damage, such as scratches. Rhodium plating also provides a brilliant shine that does not fade over time.
Sterling alloy can also be plated with oxidized silver. This method of processing jewelry protects and decorates the surface, adding an aging effect. The decorations give a very attractive look.
To increase strength and anti-corrosion qualities, a gilding method is used. This coating is called galvanic. It adds a noble look to the product. The gilding method is used to make watches.
What is specific gravity?
Today we are talking specifically about noble (precious metals). There are only four of them used in jewelry:
- Gold;
- Platinum;
- Silver;
- Semi-precious copper.
Let's start with the fact that all metal products that have the same volume, but cast from different metals have different masses. The weight of the product directly depends on its volume. In other words, the ratio of the volume of the alloy to its mass (kg/m3) is the specific density . Specific gravity is the same as density. That is, a quantity that is the ratio of weight to volume. Calculation formula: Y=P/V, where P is weight and V is density.
Metals in their original form are almost never used in jewelry. The likelihood of encountering jewelry made of pure gold is negligible. Why? Because it's impractical. Pure metal is too soft; if you pour jewelry out of 100% gold, it will bend and deform. Therefore, each of the precious metals requires improvement. To increase strength and wear resistance, add shine and change the shade, jewelers use ligature , that is, impurities. An alloy with added impurities has a different specific gravity, which differs from the specific gravity of pure gold, silver and platinum.
The following is used as a ligature:
- copper;
- nickel;
- silver;
- zinc;
- palladium;
- indium;
- germanium.
Possible impurities
Almost any metal in its natural state has a certain amount of some impurity. Their presence directly affects various physical characteristics, and this also affects the cost. Impurities affecting silver:
- Nickel. If it is contained less than 1%, the density of the alloy will increase; if it is more than 2.5%, the metal will become very brittle.
- Tin. It can reduce the melting point, but when it is more than 9%, the alloy will be brittle.
- Lead. This metal is considered harmful, so people usually try to avoid its presence.
- Aluminum. If it is more than 5%, the final alloy will become very brittle. The acceptable value is less than 5%.
- Zinc and cadmium. These metals are added to make solder. This alloy is used for repairing or soldering individual elements of jewelry. Also, the presence of zinc and cadmium reduces the melting point.
- Silicon. You can add a maximum of 1.5%. Otherwise, the metal will lose strength.
- Carbon. This is a harmful impurity that is usually disposed of. This element makes the alloy very brittle.
- Phosphorus and sulfur also degrade the quality of the alloy.
Electrorefining is a process by which silver is purified in an industrial setting. The method involves suspending the metal in an electrolyte bath containing silver nitrate. A silver alloy is used for the cathode, and titanium or pure metal is used for the anode. After electrolysis, pure silver remains on the cathode, and impurities remain in the space, which is filled with fiberglass.
Metal smelting
All alloys very quickly and easily begin to react with oxygen during melting, so this process is carried out in a special graphite crucible, which is previously covered. This vessel is preheated. This allows you to completely remove dirt and moisture from it. If a ceramic crucible is used, then coal is added when the metal is melted. To avoid oxidation, copper phosphate or phosphorus may be used.
When a graphite crucible is used, the use of any additives becomes unnecessary, since oxidation will be very small. Further processing will remove it.
The appearance of the surface of the molten metal during casting provides a lot of important information. If the temperature is correct, the silver will have a pink tint and a shiny surface. The top layer is removed, since it contains copper oxide. It is very important to maintain the correct temperature, as overheating will affect stability and uniformity.
Determination of sample by density
Archimedes invented the method for determining the percentage of pure metal in an alloy. This method is based on the fact that the silver will be immersed in water . To calculate the density of any material, you need to know 2 basic quantities - mass and volume.
It’s very easy to find out your weight—you just need to use a scale. But difficulties arise with calculating volume when you need to find out the value for a product that has an irregular geometric shape. To do this, measure the volume of water that is displaced when this product is immersed. If you divide mass by volume, the result is density. Each sample has its own value.
This method allows you to distinguish different metals. For example, stainless steel is often used in jewelry. It is difficult for an inexperienced person to distinguish what exactly the jewelry is made of. But the definition of density gives a clear answer.
