B e r y l l i u m

Rare Metals

You have probably heard of such metals as germanium, niobium, thorium, etc. They are called rare metals. Why are they called rare? In the first place, because some of them are not plentiful in the earth's crust. And in the second place, because some of them are difficult and rather costly to extract from their ores, that is they are more difficult to work than the common metals.

And where are rare metals found? Are they found only in the earth's crust? Rare metals are found not only in the earth's crust, but also on the ocean bottom, in plants and animals. For example, titanium has been found in animal flesh and bones, cobalt in marine organisms, lithium in plants and so on.

Rare metals, as you will see presently, have different physical and chemical properties, so they naturally fall into several groups. For instance, lithium, cesium, beryllium are called light rare metals. Molybdenum, rhenium, tantalum, niobium, vanadium, zirconium are referred to as refractory metals.

Vanadium

Here is a short story about vanadium, wonder-metal. Vanadium was discovered in 1801, but many years had passed before metallurgists realized its great value. It was first discovered by Manuel del Rio, Professor of Mineralogy at the School of Mines in Mexico City, in lead ore. M. del Rio named the new metal erythronium because its salts became red when heated.

In 1830 Sefstrom found an unknown metal in the iron ores from Sweden. And he named the metal vanadium in honour of the Scandinavian goddess Vanadis. He gave it this name because of its beautiful many-coloured com­pounds. After Sefstrom's discovery Wolher found that erythronium and vanadium were the same metal.

As far back as 1906 vanadium was the world's rarest metal. It is still very valuable but it is not so high-priced as earlier. It is more valuable now for what it can actually do.

And here is what it can do. When it is added to steel (in proportions of about two parts of vanadium to a thousand parts of steel) it does miracles. It makes an excellent alloy. Our finest high-speed tools made of tungsten and chromium get such brutal use that they would, most certain­ly, wear out in a very short time, if vanadium were not added. But a little bit of vanadium gives them a long life.

Vanadium steel is harder in the red-hot state than when it is cold. It is these wonderful qualities of vanadium steel that give us a smooth train ride at 100 kilometers an hour.

Europe was using vanadium at a time when vanadium was quite unknown in the United States. Then in 1906, Henry Ford discovered how valuable this metal could be. That year Henry Ford went to Palm Beach to watch his model K. in an automobile race. At that time it was the best car on the mar­ket in the United States. But model K. was badly beaten by a French car. After the race Ford picked up a small part from this French car and had it analyzed in the Detroit laboratory.

In this way he discovered that the part was made of an alloy of steel and the rare metal vanadium. At that time there was no one in the United States who knew how to make this alloy. Ford had to get an engineer from Europe. He got an expert from England and the English engineer made the first vanadium steel commercially. This incident revolutionized automobile manufacture: it was soon found that vanadium steel had three times the tensile strength of ordinary steel.

Luckily, for the automobile industry, the richest vanadium deposits in the world were discovered in the same year, i.e. 1906, in Peru. This mine remains the largest single source of vanadium in the world although in Colorado and other Western states fair quantities of vanadium are mined.

About the same time vanadium was found to be valuable in other fields. Generally speaking, vanadium is a "must" where strength and hardness are needed. Because vanadium is tough and long-wearing it is often referred to as a "miracle-metal."

What is vanadium like? Pure vanadium is a bright, silvery, ductile metal. But it is extremely difficult to get it pure. It is stable in air and is not affected by water at room temperature. When vanadium is finely divided and thrown into a flame it burns very brightly.

Vanadium, as you know, is used in motor-cars, locomotives, trucks, buses and other mobile machinery. The steel helmets that were used in both World Wars were made of vanadium steel. Vanadium-bronze is applied in the aircraft industry. But vanadium-copper alloys are more suitable for making ship parts as well as submarine parts. It is because vanadium-copper alloys can easily resist salt water.

Vanadium is also used in precious metal alloys from which jewelry is made. Vanadium hardens gold and may be applied for coins and dental bridges.

Vanadium is now applied in medicine, too. It is used in treating venereal diseases and anemia. Doctors got good re­sults in the case of anemia; it gave a better appetite and a gain in weight. Vanadium has proved to be effective when given for dia­betes, neurasthenia and rheumatism. Recently it has been tried in treating ulcers and infected wounds, but the results have not been quite satisfactory.

Lithium

Let's start with lithium and see why it is so called, what it is like, and where it is used.

Lithium comes from the Greek word lithos which means "a stone." It is a very light, soft, silver-white metal. It is so soft that you can cut it with a knife. And it is the lightest metal, in fact, the lightest of all solids. It is five times as light as aluminium — a cubic foot of aluminium weighs 169 pounds, while a cubic foot of lithium weighs only 33 pounds. Li­thium is even lighter than cork and will float on water and oil. It is so light, indeed, that two men might easily lift an aeroplane made from lithium. But you can make neither an aeroplane nor even a spoon from lithium. Why? Because lithium readily combines with air and water as it is so unstable. And do you know what might happen if you stirred hot tea with a spoon made from lithium? The spoon would simply disap­pear.

But lithium has come into use quite recently. For many years after its discovery in 1817 lithium was a useless curiosi­ty. In the early 1880's, Thomas Edison began using it in electric batteries. And it is still used for this purpose in two-way signal systems and in the television picture tube. Now it is also used in the making of vitamin A and other drugs.

Li­thium has other interesting uses: in the manufacture of soap and lubricating oils. In fact, a lubricating oil that contains lithium may be very successfully used both in the tropics and in the Arctic regions. In 1951 the United States of America used 50% of its lithium for lubricating oils.

Lithium is still costly, but it is generally used in small amounts. One exception is the H-bomb. This bomb may use as much as five tons of lithium. Though it is still high-priced it is cheaper and more plentiful than uranium. And weight for weight, lithium could give three times more energy than uranium.

During World War II lithium was used for purifying air in submarines, de-icing aeroplanes and for making signal flares.

When the war was over, it seemed that lithium would no longer be needed. But resourceful scientists found other uses for this wonder-metal. They soon discovered that lithium was good for purifying copper and bronze castings, that it was valuable in steel-making and could be used in air-condition­ing units.

Most of it comes from the United States, Canada and South Africa. The metal is widely distributed but in small deposits. Mining and refining costs are high. That's why lithium is still high-priced.

Cesium

Now let's take a look at cesium, another rare metal. It is a silver-white metallic element, which was named cesium from the two sky-blue lines in its spectrum. It comes from the Latin word caesium meaning 'bluish-grey'. Chemists call it a touch-me-not because it readily ignites when combining with air, and explodes when it combines with water.

Another remarkable thing about cesium is that it is an easily melted metal. It will readily melt at the touch of a warm palm of the hand.

It was discovered by two famous German chemists: Robert Bunsen and Gustav Kirchoff in I860. It was discovered so late because it is the most active of the metals and never found pure. It tarnishes so quickly that it must be kept in kerosene.

Where is this valuable metal found? Mostly in the earth's crust. But you can find small traces of cesium in mineral springs and the ashes of certain plants.

Though cesium is a rare metal it has many important uses. And since it is very active a small amount of it is enough to bring about good results.

One of the earliest uses of cesium was in the manufacture of radio vacuum tubes.

But its use in the photoelectric cell is now more important. And as you may have heard the most common use of the pho­toelectric cell is with the "electric eye," which is a wonder: it can do extraordinary things. For instance, when a worker gets too close to a dangerous unit of machinery the "electric eye" gives a warning signal. And it is the cesium that does the trick.

Cesium does play an important role in television. The te­levision camera, as you know, has a tube with a plate that is a few inches in area. This plate is covered with more than a million silver dots. Each of these dots is separate. But when we look at the plate all the dots seem to be joined together.

These silver dots are coated with cesium. And this is what makes the television tube work. When a beam of light strikes the cesium, it gives off electrons, just as in the case of the photoelectric cell. In the television camera the powerful lights strike the millions of dots and make them give off lots of electrons. In this way we get contrasts of light and darkness because there is a lot of light in some areas and much less light in others.

And now cesium is proving to be useful in pure science. At the Laboratory of Nuclear Science at the Massachusetts Institute of Technology, for example, a group of scientists has developed a cesium clock. It is so accurate that it won't lose more than half a second in 2,000 years. Physicists are planning to use this clock in the experimen­tal test of Einstein's Theory of Relativity. They also believe that the cesium clock will have many other scientific uses, because it is so accurate.

A cesium astronomical camera is another marvelous inven­tion. It was devised by a group of French astrophysicists. It is based on the electronic properties of cesium. Up to now it was difficult lo photograph stars that are millions of miles away because the light from these bodies is so faint. And so long exposures of the image were necessary. Besides, long exposures, say, of eight hours, resulted in distortion. The new cesium camera strengthens these faint beams 20, 000 times. And in some cases it reduces the exposure to four minutes. In this camera the light corning from the stars strikes a thin glass plate, which is coated with cesium and antimony. When the light strikes the plate it gives off lots of electrons. And these are controlled lo follow the path of the light source. The apparatus is mounted on a telescope with a mirror.

B e r y l l i u m

Let's take a glimpse at beryllium. Very little is yet known about it. It is a hard, silver-white metal, named after the mineral from which it is extracted. The name of the mineral itself is beryl. It is ductile at higher temperatures and may be easily rolled into sheet.

Beryllium is not found native. It does not occur in large deposits but is widely scattered in various rocks. It is found in the Urals, Brazil, Argentina, Chile, the United States of America and South Africa.

Beryllium first came into use during World War I. It was then applied in alloys with copper. This remarkable metal is used in watch-making. There are now on sale beryllium-copper-watches that are not affected by a magnetic field. But beryllium is still a rare and high-priced metal. And, most likely, it will not become cheap in the near future.

Molybdenum

Molybdenum comes from the Greek word molybdos which means "lead." It is a hard silver-white metal. And like graphite it can be used for writing or drawing. It was discovered in the Western world in 1778.

Here is a bit of intriguing history. Many years ago some German engineers found a sword. It turned out that was made by the famous Japanese craftsman Masamune in 1330. They got interested in the curious sword and made a chemical analysis of it, which showed that it was made of molybdenum steel.

Now taking a look back we can guess why the Germans wanted to gain a foothold in Shantung Province in China at one time, and they did gain it after the Boxer Rebellion of 1900. We may well suppose that they wanted to occupy it in order to control the source of this molybdenum steel.

Curiously enough, during World War I when the Japanese captured the port of Tsingtao in Shantung they found a German cannon which was made with the molybdenum steel.

Nowadays molybdenum is one of the most valuable metals used in making high-quality steel-alloys. It is also applied in manufacturing pigments for dying furs, cotton fabrics, leather and woolens.

Today almost the whole world s supply comes from the molybdenum mine in Colorado (USA). But it is also mined in Siberia and Georgia.

Rhenium

Fairly little is known about this hard and very rare metal. It was discovered by Walter Noddack in 1925. He named the metal rhenium after the Rhine-river.

Since this metal is still rare its uses are naturally limited. Where exactly is it used? It is good for fountain-pen points and self-writing devices, because it is a very hard metal. High-precision instruments are also made from it. It is also used in electrical engineering. American scientists are doing much experimental work with rhenium trying to find new uses for this metal, which can replace tungsten.

Rhenium is rare because it is found in small con­centrations. It is widely distributed in some minerals but in very small concentrations. For example, it may occur in concentrations as high as 10-21 parts per 1,000,000 in molybdenum ores and even to a lesser extent in copper ores.

Cerium

Cerium is a rare-earth metal. It is supposed to be the most plentiful of all the rare-earth group. It is a metal of iron-grey colour that is slowly oxidized in the air. It is so soft that it can be cut with a knife. It reacts rapidly with boiling water and burns very brightly when heated.

Cerium was discovered in 1803 by J. Berzelius and W. Hisinger working together and independently by M. Klaproth. The metal was named after the asteroid Ceres which had been discovered in 1801. Though it had been discovered in the early 19th century it came into use only quite recently.

Today cerium is much used in the glass and ceramics industries. It makes the glass transparent and pure and gives a wonderful bluish colour to porcelain when mixed with molybdenum. Lenses for telescopes, cameras and other devices as well as sun-glasses are made from cerium. Gems, too, are now made from cerium. Powdered cerium is very good for making beautiful rubies, artificial gems that look like real ones.

Hafnium

Let's take a short look at this rare metal, which was a la­boratory curiosity for many years, and which, in fact, remains a curiosity because little is known about it to-day.

It was discovered by D.Coster and G.C. de Hevesy in 1923. They named the metal hafnium, which is the Latin for Copenhagen, the place where it was discovered.

But scientists still disagree much among themselves today as to which group of metals hafnium should belong. It is in the rare-earths group. But many chemists believe it is wrong to include it in this group. They think it is more like zirconium than the rare-earths. So the argument goes on.

Hafnium-bearing minerals are found in beach-sands and river gravels along with monazite. It is mined in the United States of America (especially Florida), Australia, Brazil, Africa and India.

This curious metal come into use only in the early 1950's when it became an important material for nuclear reactors. Has it found any other important uses since then? It has. It is applied in the ceramics industry and electrical engineering. It is good for making hard alloys. But its most important use is in the building of atomic submarines.

Thorium

Thorium is another radioactive metal. Let us start with the discoverer. In 1815 the famous Swedish chemist Berzelius thought he had obtained a new element from gadolinite, a mineral. He named it thorium, in honour of Thor, the Scandinavian god of thunder. When in 1828 Berzelius did discover a new metallic element in a mineral now called thorite he reapplied the name of thorium.

Is thorium of much value today? It has important industrial and scientific uses today. It is especially valuable as a fuel for nuclear power reactors. It is used in some alloys. Electrical engineering has found it to be good for electrodes: thoriated tungsten electrodes are made from it.

Is thorium found in many minerals? It is found in over a hundred of minerals, mostly in such minerals as thorite, thorianite and monazite. It is mined in Brazil, India, Ceylon, Indonesia, Russia, Australia, the USA, South Africa, Korea and Canada.

Thorium is a poisonous metal because it is radioactive. It may do much harm when it enters the body. It may settle in the liver, kidneys, spleen, etc. and cause much painful irritation. And, naturally, those who have to handle thorium metal must be protected in every possible way from poisoning. This makes the manufacture of thorium metal difficult.

Generally speaking, thorium is a metal of the future. Its uses have not yet been fully studied. Not much is known about its technology either.

Palladium

Palladium is altogether different from the metals we have discussed above. It is a precious metal, one of the six platinum metals.

What is it like? It is silver-white, ductile and easily-worked. And here is something about its discovery.

It was William Wollaston who first got palladium from crude platinum. That happened in England in 1803. But he did not want to announce his discovery in the customary way. He made an anonymous announcement of the new metal. And because he chose to advertise the new metal in this unusual manner scientists believed that it was not an element but an alloy of platinum and mercury.

Then in 1804 William Wollaston explained all. He gave a clear and full picture of his discovery of the new metallic element. He named it in honour of the newly discovered asteroid Pallas. Pallas was the mythological goddess of wisdom.

Palladium is a precious metal, but is it used in every-day life? It is. It does not tarnish in the air at ordinary tempera­tures. So it is often used instead of platinum in jewelry, e. g. for earrings, bracelets, brooches, etc. While the beaten leaf of the metal is good for decorative purposes.

Dental alloys are made with palladium too. When palladium is mixed with gold a sort of white gold is obtained. This alloy is now used by dentists.

But palladium is not good for making astronomical and other fine instruments as it is too light. It is lighter than platinum.

Generally speaking little as yet is known about this cu­rious metal. Scientists are on the look-out for new uses.

Iridium

Indium like palladium belongs to the platinum family. What is the origin of the metal's name? Iridium comes from the Greek word iris which means «a rainbow». It was discovered by the famous British chemist S. Tennant in 1803.

What is it like? It is a lustrous steel-white metal and it is very dense. In fact, it is one of the densest solids known. Iridium is harder than steel. To be exact, it is harder than most steels. And, quite naturally, like most hard substances it is very brittle. It becomes pliable when it is heated. And like palladium it does not tarnish at ordinary temperatures.

Today much of iridium goes into platinum alloys to make them harder.

The alloys, that is, indium-platinum alloys, are good for electric thermometres or pyrometres. These instruments are used to determine temperatures during the working of metals, and they operate with great precision.

Fountain-pens are tipped with iridium now. Though iridium was discovered a long, long time ago it has not found many practical uses.

Osmium

Osmium is very much like iridium: both are platinum metals. But it is denser than iridium. In fact, it is the densest of all metallic elements. And it is hard. At any rate, it is hard enough to scratch glass. And because it is hard it is na­turally very brittle. It is blue-white.

Osmium is derived from the Greek word osme - "odour." And it was S. Tennant, a British chemist, who discovered it in 1803, the same year that he discovered indium.

Nowadays osmium has many practical uses. It is suitable for tipping fountain-pens like indium. And perhaps the fountain-pens that your parents used for writing at school were tipped with cither indium or osmium.

Osmium is used in medicine. Doctors find it good for a number of diseases. They believe it is a fine remedy for epilepsy and neuralgia. They even treat cancer with it. Of course, it is given in very small doses because the compound is poisonous. About 10 mg is the maximal dose prescribed. Drops are given for neuralgia. And the close is ten drops of a 2% solution.

Most likely, scientists will find many more interesting uses for this wonderful metal.

Rhodium

Rhodium is very much like aluminium. It is a whitish-grey metal with a bluish tint. And how does it compare with other platinum metals, for instance, osmium and platinum? It is softer than osmium and melts at a lower tempera­ture. And it is less ductile than platinum.

Its name is derived from the Greek word rhodon, which means "a rose." It was given the name by S. Wollaston, its discoverer, after the colour of its salts, which have beautiful reddish tints. S. Wollaston discovered the metal in 1803.

Rhodium is not very brittle at ordinary temperatures as some of the other platinum metals. It readily mixes with many metals. When it is mixed with gold or silver it resists even aqua media.

Engineers believe that rhodium is most useful for plating. They think it makes many things long-lasting. It does make long-lasting those parts of machines which have to stand brutal usage and remain strong and beautiful.

Here are some examples of machine parts and devices that use rhodium. Automobile headlight reflectors, for instance, are coated with this beautiful bright metal. Many instru­ments and small devices that are used in specialized fields are either plated with rhodium or made from rhodium alloys. For example, surgical instruments are now coated with rhodium to make them long-lasting.

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