Gold and silver alloy

The first precious metals to attract human attention were native gold and silver. A natural alloy of gold and silver called electrum, was known in ancient times. Jewelry, coins and dishes were made from it, some of which have survived to the present day in the form of museum exhibits. And until now, decorations from electrum are in demand. Let us consider in more detail what is the peculiarity of this alloy, as well as what decorations it is made of.

Electrum is an opaque mineral with a metallic sheen, which is one of the varieties of gold nuggets. An artificial alloy of gold and silver consists of one part of silver and three parts of gold. However, the natural composition of the electrum does not contain such a strict ratio of one to another. This metal has a beautiful golden yellow color, less often - white or greenish. It is because of its color that the mineral received its name: in translation from the ancient Greek language, electrum means "amber".

Sometimes this alloy is called "white gold", but this is not entirely true. In our country, white gold indicates an alloy with platinum, but in European countries white gold is obtained from artificial electrum. When buying jewelry, you need to remember about this difference.

To strengthen the structure of gold very often use various alloys: with silver, copper, platinum, palladium. The main component of the ligature for the yellow metal is, of course, silver. It reduces the melting point and allows the alloy to become more malleable, and also adds resistance to abrasion and mechanical damage to the finished product.

In jewelry, electrum is called Green gold but, in addition to a mixture of gold and silver, it may also contain cadmium and copper. Due to the toxicity of cadmium in the Russian Federation and European countries, it is not added. However, some countries still use cadmium in the smelting of green metal.

The color of the alloy is regulated in accordance with GOST 30649-99 from 07/01/2000 and is four samples:

• ZlSR 585-415 (green),
• ZlSrM 585-300 (yellow-green color),
• ZlSr 750-250 (green color),
• ZlSrM 750-150 (greenish-yellow color).

Samples differ in the percentage of precious metals and the presence (or absence) of copper in the ligature.

Green gold is a rather fragile alloy. The main feature of electrum is the inability to accurately determine all chemical and physical properties due to differences in the percentage of elements in the nugget.

In ancient times, ritual weapons, jewelry, the first minted coins and dishes were made from an alloy of gold and silver. Sometimes nuggets literally lay underfoot. Due to the fact that the metal was located almost on the surface of the soil, it was almost completely collected during the gold rush. Therefore, for the most part, such an alloy is currently receive exclusively by artificial means. The addition of silver leads to the fact that the metal becomes more ductile, therefore it is easier to process at jewelry enterprises.

The main properties of the alloy are:

• oxidation resistance;
• significant melting temperature;
• high density;
• Mohs hardness - 3 points;
• high coefficients of electrical conductivity and conductivity;
• resistance to dissolution in acids (except aqua regia and hydrocyanic acid).

In the manufacture of artificial alloys of gold and silver, some nuances must be taken into account.

1. First, the yellow metal is melted, and then any other components are added to it.
2. In no case should copper be added before silver or other noble metals. The reason is this: due to the properties of copper, the alloy may stiffen unevenly.
3. Particular attention must be paid to the melting point. Strict control of this parameter is necessary so that the metal does not overheat and does not become brittle.

An approximate sample of the nugget can be determined as follows: run a nugget over the “assay stone”. A shiny line should remain on its surface, the color and luster of which is compared with the reference indicators.

Native gold has several varieties.

1. Electrum (or silver gold).
2. Cuproaurite (or auricuprid), otherwise called copper (red) gold. It contains, in addition to the yellow metal, a significant percentage of copper. When the copper content is 9-20%, the color becomes pinkish, at 25-30% - red. Because of this color, the name of such nuggets came to be - pure gold.
3. Bismuthauurite (or bismuth gold). Contains up to 4% bismuth.

• Gives birth (generic gold). Contains up to 43% rhodium.
• Porpecite (palladium gold). The name is given for the region of Porpece in Brazil, contains from 5% to 12% palladium. The nugget is white.
• Iridium gold. Contains up to 30% iridium in its pure form or with impurities.
• Platinum gold. This alloy contains up to 11% platinum or mixture.
• Magnetic gold. Contains iron impurities.

Noble metal alloys used in the jewelry industrywhere various ornaments are made of them, for example, rings, chains, pendants and earrings. IN dentistry they are used in the manufacture of bridges and crowns.

In the chemical industry Separate alloys are needed to cover pipes that are used to transport aggressive chemicals. In the electronics industry there is a need for alloys of gold with silver for the manufacture of current-collecting electrodes. In microelectronics alloys of precious metals are used in the form of galvanic coatings of connectors and contact surfaces. And also they are used for the manufacture of valuable award paraphernalia in sports (cups, medals). IN nuclear field also it is impossible to do without precious metals and their mixtures.

Yellow metal alloy products will always be in demandbecause, in addition to all of the above, they are also a good investment contribution to the future.

Read more about another popular precious metal alloy - pure gold - in the video below.