Table of silver density depending on the sample + how to determine the alloy by density

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.

What is heavier - gold or silver?

What is heavier - gold or silver?

• Gold is definitely heavier than silver. After all, its specific gravity, that is, the weight per unit volume is greater. I don’t remember how long ago I finished school, but it seems almost twice as long. Silver is correspondingly lighter.
• Of course gold is hard. After all, gold is a heavy metal, and silver is light. Even if you weigh gold and silver, it turns out that gold is heavier than silver. Many people do not like to wear gold because it is heavy for them. And they prefer to wear silver.
• If we have two pieces of gold and silver, and they are the same size, then after we weigh the gold and silver, which are the same size, we will see that the gold weighs more than the silver.

  As a result, we can say that gold has more weight than silver.

• Gold is heavier.

  Au (gold) atomic number 79 (atomic mass 196.96654)

  Ag (silver) atomic number 47 (atomic mass 107.8682)

• The answer is simple. Gold is one of the heaviest metals; with the same volume, it weighs more than silver. Judge for yourself: the density of gold is 19.3 g/cm3, but the density of silver is 10.5 g/cm3. As you can see, the density of gold is almost twice the density of silver; accordingly, with the same volume, a gold bar will be much heavier than a silver bar.
• In order to determine which metal is heavier, you need to know the weight of each metal and then compare. What we have:

  The (atomic) mass of gold is 196. The (atomic) mass of silver is 107. Therefore, gold is heavier than silver.

• Of course, look at Mindeleev’s table: Gold is heavier!
• Remember: gold is always heavier than silver, because gold is a heavy precious metal, but silver is lighter, it’s easy to check even on your hand, easy to distinguish even when a person wears it on his body
• More useful information! When I make a product in silver according to the established matrix, it weighs 2 grams, and if I planned to cast the same jewelry in gold, then I do it like this: 2 * 1.425 then the gold required for the same mold is already 2.85!
• Well, no matter how you look at it, gold will always be heavier than silver. If these natural substances are present in equal volumes. Look at the periodic table and everything will immediately become extremely clear: the specific gravity of gold is 196.9 and silver is 107.8.
• And here is the correct answer :). Both bars have the same weight. But the mass is different (it’s easy to even calculate how much). 1 kg of gold takes up less volume (about 50 cubic cm) than 1 kg of silver (95 cubic cm). This means that 1 kg of silver on Earth (!) is subject to a greater Archimedean force, therefore the mass of this ingot is greater. Difference 0.045 cu. dm. Air density 1.29 g/cubic dm. This means that the difference in mass is about 60 mg. Quite a lot for a precious metal :). I don’t know if anyone has tried to profit from this, for example, by weighing ingots at the pole and at the equator, where there will even be a difference in weight!
• With the same volume, the weight of gold is greater than that of silver. Everything depends on atomic mass. The atomic mass of gold is 196, and that of silver is 107. It turns out that gold is almost twice as heavy as silver. Even when you wear jewelry made of gold or silver, you feel that gold is heavier.
• It's simple. We remember from school that mass is equal to density multiplied by volume. Accordingly, we are looking for a metal with a higher density. Silver (10,500 kg per cubic meter) is lighter than gold (19,320).
• The atomic mass of gold (Aurum) is 196.96654 and the atomic mass of silver (Argentum) is 107.8682. From this we can clearly conclude that, with the same volume, gold weighs more, that is, silver is almost twice as light as gold.
• And only D.I. Mendeleev’s table of elements can help you, or the table of specific gravities of various substances, and in this case, metals. As for the periodic table, where they operate with the atomic weights of elements, here we can only give a qualitative assessment, one hundred heavier - gold or silver.

  And a comparison of the atomic masses of gold (197) and silver (108) resolves the issue not in favor of silver, and the answer is given:

  gold is heavier than silver.

  But you can determine the weight specifically by the volume of a substance using the table of specific gravities.

  Density of gold = 19321 kg m^3, density of silver = 10500 kg m^3.

  Which also indicates that the same volume of gold is heavier than silver.

• Gold is heavier and has a much higher atomic mass. If we take exactly identical pieces of gold and silver, and visually they will look the same, i.e. there will be exactly the same volume, but the mass will be different, the gold will be heavier.

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World deposits

Silver is mined from fundamentally different types of deposits. There are only two such types. They are divided as follows:

1. 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.
2. 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:

1. It has the lowest melting point when compared with other precious metals.
2. Dissolves only in mercury, nitric and sulfuric acid.
3. Does not react with substances.
4. It cannot be dissolved in aqua regia.

Let's sum it up

People always ask me how to tell if silver is real or fake. After reading this review, you learned, dear readers, that silver is extremely thermally conductive, so you can use a simple method - put it in boiling water (if the product does not have stones). It will heat up instantly, but will cool down just as quickly, unlike a fake.

This is important to know, since you should only buy real, high-quality products.

Silver alloys are in demand both in the jewelry industry and in medicine due to their antimicrobial effect; in nanotechnology, in microelectronics (don’t forget that this metal is an excellent conductor). This is a natural, exhaustible resource with a lot of special properties. Share this information on social networks, subscribe to us to learn new and useful information. See you soon!

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:

1. 960 sample. Almost pure metal. Used for filigree work.
2. 925 sample. It is often used in jewelry.
3. 875 sample. Not a very popular alloy among jewelers, as it has a yellow tint.
4. 830 sample. Used in industry.
5. 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.

Density and specific gravity of 925 silver

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.

World deposits

Silver is mined from fundamentally different types of deposits. There are only two such types. They are divided as follows:

1. 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.
2. 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:

1. It has the lowest melting point when compared with other precious metals.
2. Dissolves only in mercury, nitric and sulfuric acid.
3. Does not react with substances.
4. It cannot be dissolved in aqua regia.

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:

1. 960 sample. Almost pure metal. Used for filigree work.
2. 925 sample. It is often used in jewelry.
3. 875 sample. Not a very popular alloy among jewelers, as it has a yellow tint.
4. 830 sample. Used in industry.
5. 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.

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.

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:

1. 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.
2. Tin. It can reduce the melting point, but when it is more than 9%, the alloy will be brittle.
3. Lead. This metal is considered harmful, so people usually try to avoid its presence.
4. Aluminum. If it is more than 5%, the final alloy will become very brittle. The acceptable value is less than 5%.
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.
6. Silicon. You can add a maximum of 1.5%. Otherwise, the metal will lose strength.
7. Carbon. This is a harmful impurity that is usually disposed of. This element makes the alloy very brittle.
8. 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.

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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.

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:

1. 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.
2. Tin. It can reduce the melting point, but when it is more than 9%, the alloy will be brittle.
3. Lead. This metal is considered harmful, so people usually try to avoid its presence.
4. Aluminum. If it is more than 5%, the final alloy will become very brittle. The acceptable value is less than 5%.
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.
6. Silicon. You can add a maximum of 1.5%. Otherwise, the metal will lose strength.
7. Carbon. This is a harmful impurity that is usually disposed of. This element makes the alloy very brittle.
8. 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.

Specific gravity of the metal. Table of densities of metals and alloys

All metals have certain physical and mechanical properties, which, in fact, determine their specific gravity. To determine how suitable a particular alloy of ferrous or stainless steel is for production, the specific gravity of rolled metal is calculated. All metal products that have the same volume, but are made from different metals, for example, iron, brass or aluminum, have different mass, which is directly dependent on its volume. In other words, the ratio of the volume of the alloy to its mass—specific density (kg/m3)—is a constant value that will be characteristic of a given substance. The density of the alloy is calculated using a special formula and is directly related to the calculation of the specific gravity of the metal.

The specific gravity of a metal is the ratio of the weight of a homogeneous body of this substance to the volume of the metal, i.e. this is density, in reference books it is measured in kg/m3 or g/cm3. From here you can calculate the formula for finding out the weight of a metal. To find this you need to multiply the reference density value by the volume.

The table shows the densities of non-ferrous metals and ferrous iron. The table is divided into groups of metals and alloys, where under each name the grade according to GOST and the corresponding density in g/cm3 are indicated, depending on the melting point. To determine the physical value of specific density in kg/m3, you need to multiply the tabulated value in g/cm3 by 1000. For example, this way you can find out what the density of iron is - 7850 kg/m3.

The most typical ferrous metal is iron. The density value of 7.85 g/cm3 can be considered the specific gravity of iron-based ferrous metal. Ferrous metals in the table include iron, manganese, titanium, nickel, chromium, vanadium, tungsten, molybdenum, and ferrous alloys based on them, for example, stainless steel (density 7.7-8.0 g/cm3), black steel ( density 7.85 g/cm3) is mainly used by manufacturers of metal structures in Ukraine, cast iron (density 7.0-7.3 g/cm3). The remaining metals are considered non-ferrous, as well as alloys based on them. Non-ferrous metals in the table include the following types:

− light – magnesium, aluminum;

− noble metals (precious) - platinum, gold, silver and semi-precious copper;

− low-melting metals – zinc, tin, lead.

Table of specific gravity of metal alloys

The specific gravity of metals is most often determined in laboratory conditions, but in their pure form they are very rarely used in construction. Alloys of non-ferrous metals and alloys of ferrous metals, which according to their specific gravity are divided into light and heavy, are much more often used.

Light alloys are actively used by modern industry due to their high strength and good high-temperature mechanical properties. The main metals of such alloys are titanium, aluminum, magnesium and beryllium. But alloys based on magnesium and aluminum cannot be used in aggressive environments and at high temperatures.

Heavy alloys are based on copper, tin, zinc, and lead. Among the heavy alloys, bronze (an alloy of copper with aluminum, an alloy of copper with tin, manganese or iron) and brass (an alloy of zinc and copper) are used in many industries. Architectural parts and sanitary fittings are produced from these grades of alloys.

The reference table below shows the main quality characteristics and specific gravity of the most common metal alloys. The list provides data on the density of the main metal alloys at an ambient temperature of 20°C.

The density of metals and alloys presented in the table will help you calculate the weight of the product. The method for calculating the mass of a part is to calculate its volume, which is then multiplied by the density of the material from which it is made. Density is the mass of one cubic centimeter or cubic meter of a metal or alloy. Mass values ​​calculated on a calculator using formulas may differ from real ones by several percent. This is not because the formulas are not accurate, but because in life everything is a little more complicated than in mathematics: right angles are not quite right, circles and spheres are not ideal, deformation of the workpiece during bending, embossing and hammering leads to unevenness of its thickness , and you can list a bunch more deviations from the ideal. The final blow to our desire for precision comes from grinding and polishing, which lead to unpredictable weight loss in the product. Therefore, the obtained values ​​should be treated as indicative.

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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.

Metal density indicators

The specific gravity of a metal is, in other words, its density. This indicator depends on two factors: volume and weight of the product. That is, if a metal product is small in size, but very heavy, then its specific gravity is large. If a piece of metal looks visually large, but is light, then its specific gravity and, accordingly, density are small. Light metals are those whose specific gravity is less than 5 g/cm3, and heavy metals, respectively, have a density above 5 g/cm3.

Over time, the specific gravity of the metal does not change. This value is constant, therefore it is thanks to this indicator that the presence of metal in the alloy can be calculated. To calculate the specific gravity of an alloy, divide the mass of the dry material by its volume in a dense state.

Specific gravity = Part of the whole / Whole x 100%

This is a formula for calculating specific gravity and is suitable for all metals. The numerator is P, the weight of the product, and the denominator is the volume of the product. For silver this value is 10.5 g/cm3. This means that silver is 10.5 times heavier than water, but almost two times lighter than gold and platinum.

The higher the specific gravity, the more expensive the metal is. Therefore, in appearance, the silver item will seem small, but in terms of weight it will be both heavy and correspondingly expensive.

Comparison of the density of silver with other metals

The specific gravity of silver depends on the fineness of the alloy. If a master alloy of another metal, such as copper or nickel, is added to the alloy, the product loses its specific gravity and density. The density of copper is 8.93 g/cm3, and that of nickel is 8.91 g/cm3. Therefore, the smaller the alloy sample, the correspondingly it is cheaper and its specific gravity is lower. You can calculate the values ​​using formulas.

This indicator is also calculated when sorting and handing over scrap metal. This is how its value is assessed. Specific gravity is an indicator of the authenticity of the metal and alloy sample. Knowing all the values, you can calculate how much pure silver is added to the product and whether it is there at all. Thus, jewelers distinguish fakes from originals in jewelry. And the apparatus used to carry out this procedure works on the principle of homogeneity of the alloy and assessment of its density.

Due to their high density and specific gravity, metals can be extracted by laundering. This is done with gold or platinum. In deposits, metals are washed from impurities, and the heaviest grains settle at the bottom. Silver is mined in a different way; it can rarely be found in free form on river banks, so the laundering method is not suitable.