I platinum and its characteristics

I. Mineralogical characteristics of natural platinum

Platinum group elements include platinum, palladium, rhodium, ruthenium, iridium and osmium. In nature, they often occur together, and together with gold and silver, they are called precious metal elements.

In mineral classification, platinum group minerals belong to natural platinum subgroup, including natural elemental minerals such as iridium, rhodium, palladium and platinum. Platinum group minerals are all equiaxed, with few single crystals and occasionally cubic or octahedral fine crystals. Generally, it is an irregular granular, dendritic, grape-like or massive aggregate. The color and stripes are silvery white to steel gray; Metallic luster, opaque. Cleavage, serrated fracture, ductile. It is a good conductor of electricity and heat.

The natural element platinum is a rare precious metal element in the earth's crust, and its symbol is Pt. The mineral name of natural platinum is natural platinum. It is a simple mineral of natural element platinum, and its chemical formula is Pt. The specific gravity of natural platinum is15.5 ~ 21.5; The refractive index is 56.5 ~ 60.0.

Second, the concept of platinum and platinum

At present, there are two misunderstandings about the consumption of platinum jewelry. First, platinum is mistaken for platinum, and the two are confused. Second, I don't know how to identify platinum ornaments with the "Pt" logo. In fact, platinum and platinum are completely different things.

1, platinum concept

The name of platinum comes from Spanish "Platinum Delpin", which means the white metal similar to silver in Pinto River. Metals smelted from platinum group minerals include palladium, iridium, platinum, rhodium and gold. Generally, platinum is made by smelting platinum ores such as natural platinum and crude platinum ores. It is a rare precious metal mainly containing platinum or completely composed of platinum, belonging to the same kind of precious metal as gold and silver.

2. The concept of platinum

Generally speaking, the full name of platinum should be "platinum". It is a platinum-free white alloy made of gold and other white metals. Among them, the percentage of gold is at most 75%. Because this alloy is white, it is called platinum.

Three. Physical and chemical properties of platinum

Platinum group metals are beautiful in color; Strong ductility; Resistance to melting, friction and corrosion; Chemical stability at high temperature. Therefore, they have a wide range of uses. Among platinum group metals, platinum is the most familiar and commonly used one. It is rarer and more valuable than gold and silver among precious metals.

Pure platinum is silvery white; It has metallic luster. The color of platinum is natural and unchangeable for a long time. The hardness is 4 ~ 4.5 degrees. The relative density is 2 1.45, and the specific gravity is 15 ~ 19 or 2 1.4. Strong ductility, can be drawn into extremely thin platinum wire and rolled into extremely thin platinum foil; Strength and toughness are also much higher than other precious metals. 1g platinum will not break even if it is drawn into a filament with a length of 1.6km .. The melting point is as high as 1 173.5℃. Good thermal and electrical conductivity. Chemical properties are extremely stable, insoluble in strong acid and alkali, and not oxidized in air. Platinum does not absorb silver and has a unique catalytic effect.

Four. Types of platinum

According to the different platinum content, platinum can generally be divided into pure platinum, iridium platinum and K gold (white K gold).

1, pure platinum

Pure platinum refers to the platinum with the highest platinum content or purity. Its white luster is natural, will not fade, and can be matched with any type of skin. It is twice as strong as gold. Its toughness is better than that of ordinary precious metals.

Pure platinum is often used to make engagement rings to show the purity and eternity of love. In foreign countries, many people think that setting diamonds with gold may lead to the yellowing of diamonds, thus greatly reducing the price of diamonds. Diamonds inlaid with platinum can keep the pure white color of diamonds, especially as engagement rings. Diamonds inlaid with platinum are white and crystal clear, symbolizing eternal and long-lasting pure love.

2, iridium platinum

Iridium platinum refers to an alloy composed of iridium and platinum. Its color is also silvery white; Has a strong metallic luster; High hardness; The relative density is high; Chemical properties are stable. It is the best platinum alloy jewelry material.

According to the different contents of iridium and platinum, it can be generally divided into the following three types, and its composition, relative density and melting point are as follows:

10% iridium platinum alloy, 2 1.54,1788℃;

15% iridium platinum alloy, 2 1.59,1821℃;

5% iridium platinum alloy, 2 1.50, 1779℃.

3.k platinum (platinum)

Because the hardness of platinum is too high, it is necessary to mix other metals to make alloys in order to reduce the hardness properly when making jewelry. In order to reduce the cost of platinum ornaments, other metals are often mixed to make alloys. Therefore, K gold appeared in the jewelry market. Moreover, people have given different meanings to K platinum. Usually, people use the first statement below.

(1), one of the meanings of k platinum.

Strictly speaking, K platinum is not platinum with low purity; In other words, K platinum contains no platinum at all. It is a misunderstanding that "K platinum is an alloy of platinum and other metals in different parts".

Because platinum is scarce, expensive and has a high melting point, it is rarely used to produce true K platinum in general countries. Gold, palladium, nickel, silver, copper, zinc and other metals are usually selected to smelt into a white alloy, which is called "K platinum". Therefore, in fact, K platinum is a white alloy made of gold and palladium or metals such as nickel, silver, copper and zinc. Its main component is still gold. The gold content is up to 75%. When gold and nickel are melted together, a white alloy is also formed. In addition, metals such as silver, copper, zinc and palladium were added. Therefore, to be more accurate, platinum should be called white gold. Platinum can't be compared with platinum in purity, rarity, durability and natural color. Moreover, it can't be marked "Pt". Only "18K" and "14K" can be stamped according to the gold content.

The fineness calculation of K platinum is the same as that of K gold, that is, it is still calculated according to the gold content. For example, the most common 14K platinum (called "40% K gold" or "226 gold" in Hong Kong and Macao markets) is made of 58.5% gold, 22.4% silver, 14. 1% copper and 5% nickel. 18K platinum (known as "60% K platinum" or "334 gold" in Hong Kong and Macao markets) is made of 75% gold, 10% silver, 4 ~ 10% zinc and 5% nickel.

(2) The meaning of K platinum in the second statement.

K Platinum is an alloy of platinum and other metals.

Gold, nickel, silver, palladium, copper, zinc and platinum can all be melted together to form K platinum. K platinum is pure white. In 14K platinum, there are 22.4% silver, 14. 1% copper and 5% nickel. In 18K K platinum, there are 10.0% silver, 5% nickel and 4 ~ 10% zinc. 40% K platinum appears in Hong Kong and other markets, with the words 14K, also known as "226 gold"; 60% K platinum, model 18K, also known as "334 gold".

Two. Platinum deposit types and platinum reserves

I. Types of platinum deposits

Platinum ore refers to the general name of platinum group metal minerals. It has many types of deposits.

1, China platinum mine

In China, platinum group metals are mainly produced in copper-nickel sulfide deposits. Among them, it is mainly produced in Jinchuan copper-nickel sulfide deposit. More than 20 kinds of platinum group metal minerals have been found in Yunnan platinum mine in China. Among them, there are mainly arsenic platinum ore, tellurium platinum ore, bismuth tellurium platinum ore, bismuth tellurium palladium ore, yellow bismuth tellurium palladium ore, iron platinum ore, sulfur platinum ore and so on. The main body of Yunnan platinum deposit with industrial value belongs to the type of poor copper, nickel, platinum and palladium deposit caused by molten hydrothermal solution in the late magmatic period. 1983, the largest jinbaoshan platinum mine in China at that time, was also one of the platinum mines with industrial value.

2. World Platinum Deposits

Platinum group metals are mainly produced in copper-nickel sulfide deposits related to mafic-ultramafic rocks (basic-ultrabasic rocks). In recent years, some new types of platinum-containing deposits have been discovered in the world. For example: black shale copper deposits containing platinum, platinum deposits in various copper-gold veins, porphyry copper-molybdenum deposits containing platinum group metals, pyrite copper deposits containing platinum, cassiterite-sulfide deposits containing platinum, uranium-sulfide deposits containing platinum and many other types.

The most famous platinum group metal deposit in the world is the copper-nickel sulfide platinum-bearing deposit in Bushveld layered complex in South Africa. Mineralization of platinum group metals is concentrated in Meilin base. South Africa is one of the three largest platinum producers in the world.

Two. Platinum reserves and production

In nature, platinum is not as abundant as gold. According to incomplete statistics, the total reserves of platinum group mineral resources in the world are about 3 1 10,000 tons. Among them, the total platinum reserves are about 6.5438+0.4 million tons. Although more than 60 countries have discovered and mined platinum ore, its reserves are highly concentrated in South Africa and the former Soviet Union. Among them, the South African (azania) platinum reserves are about 65438+200,000 tons, of which Transvaal platinum mine is the most famous and the largest platinum mine in the world. The reserves of platinum in the former Soviet Union were 1.866 tons. Natural platinum weighing 8-9 kilograms was found in the platinum mine of Ural placer, and natural platinum weighing 427.5 grams was also obtained in the primary mine. Their total reserves account for 98% of the world's total reserves.

The annual output of platinum in the world is only 85 tons, far less than that of gold. Only a few countries in the world produce platinum. South Africa's platinum production accounts for more than 80% of the global total production; Most of the rest are made in Russia. The annual output of platinum in the world is only 5% of that of gold.

Third, the application and value of platinum

Platinum has excellent properties and is widely used. In the jewelry industry, it is mainly used as decorations and handicrafts. In the chemical industry, it is used to manufacture advanced chemical containers, platinum crucibles, electrodes and catalysts for accelerating chemical reactions. Platinum-iridium alloy is the material for making fountain pen nib.

First, the discovery and preliminary application of platinum

People's understanding and utilization of platinum is far behind that of gold, with a history of only about 2000 years. Archaeological data show that in more than 700 BC, the ancient Egyptians were able to process platinum into platinum ornaments with high technical level. Long before Columbus discovered the New World, white gold ornaments were also popular among Indians in Central America. However, people in other areas know nothing about platinum. Until the beginning of16th century, the Spanish colonial empire was gradually formed, and a large number of Spanish adventurers flocked to Africa and America to search for gold and treasures. At that time, when searching for gold in the rivers of Ecuador, it was repeatedly found that there was a white metal mixed with gold, which was actually precious platinum. However, due to the underdeveloped science and low recognition ability at that time, faced with dazzling platinum, those colonial rulers called it "inferior broken silver" and abandoned it.

1748, Antonio Roya, a famous Spanish scientist, discovered silver-white natural platinum in Pinto River Gold Mine. After careful study, he found that natural platinum has very stable chemical properties, excellent ductility, high melting point and high relative density, which is obviously different from metallic silver. As a result, Anthony became the first scholar to study platinum in detail.

1780, a skillful craftsman in Paris made platinum rings, brooches and platinum necklaces for King Louis XVI and Queen of France. Therefore, Louis XVI and his wife became the first recorded people in the world to own platinum ornaments. Since then, the reputation of platinum has greatly improved, and it has leapt above gold ornaments, and it has been favored by the royal family, dignitaries and wealthy businessmen.

Second, the application of platinum with different purity

The hardness of pure platinum is small, so in order to increase the hardness, a certain proportion of precious metals such as palladium, rhodium and iridium must be added. Pt950 contains 5% palladium, rhodium and iridium, and its hardness is still relatively low, so it is generally used in plain platinum jewelry. Pt900 contains 10% palladium, rhodium and iridium, and its hardness is just suitable for inlaying ornaments. At present, most platinum rings are made of Pt900; However, a few manufacturers use Pt950 to make platinum ring holders.

Because metals such as palladium, rhodium and iridium are rarer and more expensive than platinum, the price of Pt900 is correspondingly higher than that of Pt950. However, many consumers have formed a habitual psychology based on their previous understanding of gold-the higher the purity of gold, the more valuable it is, and applied it to the relationship between platinum quality and price. Therefore, some merchants take advantage of this, deliberately marking the price of Pt950 higher than Pt900, misleading consumers to buy, thus obtaining high profits, which is bound to be suspected of fraud.

Third, platinum is expensive.

In nature, platinum reserves are rarer than gold. The annual output of platinum in the world is far less than that of gold. The global jewelry industry consumes only 3% platinum every year. Coupled with the high melting point of platinum, it is more difficult to purify and smelt platinum than gold, and the energy consumption is higher. Moreover, processing platinum requires a higher technical level than processing gold. Therefore, platinum is a rarer and more precious precious metal than gold, silver and other precious metals. Platinum is better than Huang Jingui.

Fourth, platinum jewelry.

Diamond inlaid with platinum can keep the pure white of the diamond, which will not lead to the yellowing of the diamond and reduce its price like gold. The natural white luster of platinum can better set off the brilliance and beauty of diamonds. Moreover, platinum is tougher than ordinary gold. Jewelry made of platinum, such as necklaces, is tough and reliable even if it is carefully processed. Gems such as diamonds inlaid in platinum are also the strongest, most reliable and safest, and inlaid diamonds are not easy to fall off.

Ultra-light platinum necklace has become a popular trend of Chinese jewelry. An ultra-light platinum necklace (1995) of 200 ~ 400 yuan is acceptable to ordinary wage earners. Moreover, platinum necklaces are short without pendants, simple and generous, and are deeply loved by women who have multiple chains for one person, one chain for one season or one chain for one dress. Experts believe that ultra-light platinum necklaces have the characteristics of elegant style and integration of eastern and western cultures, and will soon be popular throughout the country.

Platinum jewelry is mainly popular in developed countries and regions such as Europe, America and Japan. Among them, the Japanese prefer platinum jewelry most, and its sales account for about 75% of the total sales of platinum jewelry in the world, so it is known as the "Platinum Power".

China's platinum group mineral resources are few, and the reserves are less than 1% of the world's reserves, which can only meet a few percent of the demand and are mainly used in industry. The production of platinum jewelry started late. At present, only a few local manufacturers produce platinum jewelry.

Platinum, like other precious jewelry, should be stored separately from other jewelry to avoid contact, collision and scratches. It should be carefully cleaned regularly with jewelry cleaning equipment, or it can be sent to a jewelry store for professional cleaning.

Five, the meaning of platinum jewelry logo

"Pt" is a unique symbol of platinum chemical elements and also a unique symbol of platinum jewelry composition. Platinum cannot be marked with the exclusive symbol "Pt". According to the regulations of the State Bureau of Technical Supervision, all platinum ornaments produced in China should be marked with the exclusive symbol "Pt".

Usually, the platinum content of platinum ornaments is expressed by a few thousandths of platinum content. At the same time, platinum content is also one of the basis for pricing platinum jewelry. Common platinum content marks are as follows:

Foot platinum: the percentage of platinum is not less than 990, and the mark "Foot platinum" or "Pt990" indicates that the percentage of platinum in jewelry is 99%.

950 Platinum: The percentage of platinum is not less than 950, and the mark "Platinum 950" or "Pt950" indicates that the percentage of platinum in jewelry is 95%.

900 Platinum: The percentage of platinum is not less than 900, and the mark "Platinum 900" or "Pt900" indicates that the percentage of platinum in jewelry is 90%.

In foreign platinum jewelry, the words "Pt", "Plat" or "PM" are usually engraved. There are standard journalists like platinum jewelry.

The platinum ornaments produced in China are printed with the words "Platinum", "True Platinum" and "Positive Platinum" in addition to the trade name. If the seal on the jewelry is "S" or "Silver", it is a silver jewelry. If the jewelry is marked with the words "red platinum" or "k platinum", it means it is not pure platinum jewelry, or it is not platinum jewelry at all.

Identification of intransitive verb platinum and its ornaments

First, a simple identification method

1, color

Platinum is silvery white or grayish white, which is between the colors of silver and nickel. Silver has a white luster and is easily oxidized with black spots or black; Fine and smooth texture; Hardness is lower than platinum.

2. Specific gravity

The proportion of platinum is significant, ranging from 15 to 19 or 2 1.4. The ratio of silver is 10.49. When you weigh platinum and silver ornaments of the same size by hand, you will find their differences.

3. Fire

The color of pure platinum remains unchanged after being heated or cooled by fire. After silver burns, its surface will appear moist red or black-red tone.

Step 4 bend

Pure platinum is easy to bend and recover; Low color, hard and brittle, not easy to bend.

Step 5 listen

When you knock, if you make a blank sound of "Toto", it is relatively pure platinum; If it makes a harsh sound and rhyme, it is low-color platinum.

6. Mercury wiping test

Using the property that platinum does not absorb silver, mercury is coated on the touchstone grinding road. If it is silver-absorbing, it is K platinum made of gold, silver and platinum.

7, nitrate test

Grinding the platinum ornaments to be identified on the touchstone, and covering the ground track with a layer of salt, which does not need to be tightly covered; Then, drop nitric acid on the salt until it is soaked; Add some hot paper ash to the salt to play a catalytic role. After 20 minutes, wash the salt and nitric acid with clear water. After work, look over here. If there is no change, its color is about 99%; If there is trace acid, its color is about 95%; If the trace amount of nitric acid is large, its color is about 80 ~ 90%; If a layer of grinding road is corroded, the trace becomes gray, and its color is about 70%; If all traces disappear, it is fake platinum.

8. Identification of spontaneous combustion of gas lamps

Put the platinum ornaments to be identified on the gas stove. If it is real platinum, after a minute or two, the ornaments will turn red and the gas lamp will ignite automatically. If the jewelry is not platinum, there is no such reaction.

9, hydrogen peroxide reaction method

Platinum is a good catalyst with unique catalytic effect. Using this characteristic, platinum can be quickly identified. Hydrogen peroxide reaction method is commonly used. The specific method is as follows: Take a little powder of the test object and put it into a plastic bottle filled with hydrogen peroxide (H2O2). If it is platinum, hydrogen peroxide will immediately roll and bubble, decomposing a lot of oxygen. After the reaction, platinum is still intact and can be recycled (only accelerating the decomposition); If it is fake platinum or other white metals, such as lead, silver and aluminum, there is no such reaction.

10, other

You can also ask the geological department for electronic probe testing.

Second, the difference between platinum and similar metals.

Platinum is characterized by silvery white color and streaks, hardness of 4 ~ 4.5, specific gravity of 15 ~ 19 or 2 1.4, stable chemical properties, insoluble in ordinary acids and easy to distinguish from similar metals.

1, the difference between platinum and silver

Platinum and silver ornaments are very popular in the market and have always been the favorite ornaments of many women. Because platinum and silver have many similarities, it is necessary to distinguish them.

Platinum is different from silver in hardness, specific gravity and chemical stability. Generally, the following simple methods are used to distinguish them.

(1), comparative color, hardness

Platinum is silvery white or grayish white; Hard texture, Mohs hardness of 4 ~ 4.5. Silver is white; The texture is smooth and delicate, and the Mohs hardness is 2.5 ~ 2.7, which is softer than platinum and can be left with nails. Inelastic, the foil is easy to bend by hand and difficult to recover.

(2) Test specific gravity

Platinum has high density and high specific gravity. Although silver is silvery white, its relative density is 10.53g/cm3, and its specific gravity is10 ~1/only 1/2 of platinum. The same volume of silver is half as light as platinum. Generally speaking, platinum and silver can be roughly distinguished by hand.

(3), chemical methods

Silver is chemically unstable, soluble in nitric acid, and emits nitrogen dioxide gas. Platinum is insoluble in nitric acid, but it can dissolve quickly in heated aqua regia. At room temperature, its dissolution rate is extremely slow, which is generally difficult to detect with the naked eye. Put the platinum sheet on the touchstone and drop a little mixture of nitric acid and hydrochloric acid. If the debris still exists, it is platinum; If the debris dissolves and disappears, it is silver.

2, the difference between metal lead and aluminum

Platinum differs from lead and aluminum in different deformation characteristics and high specific gravity. Metal lead and aluminum are inelastic and cannot be recovered after deformation; And the specific gravity is much smaller than platinum. The specific gravity of lead is 1 1.36, and that of aluminum is 2.7, which are about 1/2 and 1/8 of platinum, respectively, and can be distinguished by hand weighing.