Mad about Science: Silver

By Ben Olson
Reader Staff

Publisher’s Note: Brenden Bobby is out this week, so you’re stuck with me.

In the world of precious metals, silver often plays second fiddle to gold. The latter is much rarer than silver, with estimates that the entire volume of gold on Earth can fit into just over three Olympic-sized swimming pools. This represents about 244,000 metric tons. Silver, on the other hand, has an estimated 1.74 million metric tons mined to date, with much more yet to be unearthed.

But, while 78% of the total gold mined is utilized for jewelry, silver has a wide variety of industrial uses, which make this metal extra precious. Industrial uses of silver accounts for about 58% of its annual demand, while gold has only about 8% of its demand driven by industrial use.

Silver is the single most conductive metal, thanks to its unique crystal structure and single valence — or outer — electron. Silver contains a higher number of moveable atoms, or free electrons. The more free electrons in a metal, the greater its conductivity.

It’s because of the conductive property of silver that it’s used in almost every electronic device. If something has an off-on switch, it probably contains silver inside of it.

For example, more than 36 million ounces of silver are used each year in auto manufacturing alone. Every electrical connection in a modern car is activated with a silver-coated contact. Whether starting the engine, adjusting power seats, opening power windows or closing a power trunk, every one of those activities is accomplished using a silver membrane switch.

The solar industry also relies on silver quite a bit. Silver powder is turned into a paste that is loaded onto a silicon wafer. When light strikes the wafer, electrons are set free and silver carries the electricity for immediate usage or storage. Even the lines on the rear window of a car that defrost ice are made from silver.

The aviation industry also relies heavily on silver. Because jet and helicopter engines run for long periods of time and at high temperatures, they require stronger silver ball bearings than other types of machinery.

Silver is also used in medicine. During WWI, battlefield wounds were wrapped in silver foil and silver sutures closed deep wounds. Silver coatings are applied to medical devices like catheters and breathing tubes to help combat germs, along with silver-embedded equipment like needles and stethoscopes.

Whenever metal pieces like pipes, faucets and electrical wires are joined, the process is known as either soldering or brazing. The processes are the same, but soldering takes place at temperatures below 840° Fahrenheit while brazing occurs at a temperature above 840° F. Meanwhile, silver ions have been added to water purification systems in community water supplies, pools and spas as a disinfectant.

Many of the higher-end telescopes and microscopes also coat their mirrors with polished silver, which reflects 95% of the visible light spectrum, making it the most reflective metal.

Silver is extracted from the Earth through both open-pit and underground methods. Once extraction is completed, the ores are crushed, ground and separated through a process called “flotation” to achieve high mineral concentrations. 

Mexico is by far the world’s leading extractor of silver, followed by Peru and China. 

(Fun fact: Mines in the Silver Valley in North Idaho have pulled more than 1.2 billion ounces of silver, 3 million tons of zinc and 8 million tons of lead out of the ground since the 1880s, ranking it among the highest-producing mining districts in history. As recently as 2021, Coeur d’Alene-based Hecla Mining Co. alone was reported to have been responsible for more than 40% of the U.S. supply of silver.)

Mining silver isn’t a recent human invention, either. Silver was one of the first five elements discovered, along with gold, copper, lead and iron. It has been mined for more than 6,000 years, with silver objects found dating as far back as 4,000 B.C.E. Part of its prevalence in ancient cultures may have to do with how malleable it is. A single ounce of silver can be made into a wire 8,000 feet long.

Along with the aforementioned uses, silver has been used for currency purposes for thousands of years. The Lydians, living in present-day Turkey, are credited as the originators of gold and silver coins, which influenced the Ionian Greeks to their west, who adopted the practice.

Silver is so attached to currency that the words for “silver” and “money” are the same in 14 languages.

Until 1965, coins minted in the U.S. contained about 90% silver, but much smaller amounts of the metal are used today. 

Sadly, most industrially used silver ends up in landfills after use and is permanently lost as a result. Don’t bother sifting through the dump looking for “poor man’s gold,” however, as the recovery process would require far more effort than it’s worth.

Finally, the word “silver” is one of the few common English words that have no rhyme.

Stay curious, 7B.