Silver
by
Silver always comes behind gold when it's time to hand out the medals but, in science at least, there's nothing second-rate about this soft, shiny metal. It's the world's finest electrical conductor and the best thing you can use to make the perfect surface of a mirror. It has lots of other amazing uses too, from coins and cutlery to antiseptic medicines and photographic film. Let's take a closer look at silver, an amazingly versatile material that people have been using for at least 6000 years!
Photo: This heliostat (Sun-mirror) is covered in a polymer (
Contents
What is silver like? Where does silver come from? How does silver behave? What is silver used for? Key data Find out more
What is silver like?
When you think of silver, you probably think of something hard,
gray, and shiny, but in its pure form silver is actually soft and
white. Like
Where does silver come from?
Chart: Which countries produce the world's silver? Chart based on estimated mine production figures for 2019. Source: US Geological Survey, Mineral Commodity Summaries, January 2020.
Although there are small amounts of silver all over the world, deposits large enough to mine economically exist in only a few countries, with over half the world's supply coming from just four nations (Mexico, Peru, China, and Australia). Most American silver (around two thirds to three quarters) comes from the western part of the country, specifically the states of Alaska (now the leading US silver-producing state), Nevada, Idaho, Montana, and Arizona.
There are relatively few dedicated silver mines, as such. Most silver (over
two thirds of the world's supply) is actually recovered as a byproduct
during mining for
Photo: Escondida Mine in Chile is the world's largest copper mine, but it's also a source of silver and gold. Daily silver production in 1999 was around 110 (short) tons (3.53 million ounces). Photo by NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team courtesy of NASA Goddard Space Flight Center (NASA-GSFC).
The pure silver is recovered by a multi-stage process that
varies according to the exact composition of the ore. Typically the ore
is crushed, smelted (heated with air) in a furnace, chemically treated
in some way (perhaps reacted with an acid, to dissolve the silver, or
mercury, which removes the silver by forming an
How does silver behave?
Silver is one of the world's favorite metals because it has all
kinds of useful physical and chemical properties. (Physical
properties are how something behaves in isolation: what it's like
when it's heated or how it behaves with
Physical properties
We've already seen that pure silver is shiny (capable of being
polished), white, and soft. Some of its properties are undeniably
"second" to gold: silver isn't so soft as gold and, for that reason, is
slightly less malleable (easy to shape) and ductile (easy to pull into
wires), though it's still one of the easiest to work of all the metals.
If you have about 30 grams of silver (one ounce), you have enough to
pull into a wire almost 50 km (30 miles) long! Silver beats gold in
other respects: it's the best conductor of
Photo: Silver is an excellent conductor of electricity, which is why its biggest use is now in electrical and electronic devices. Here's an example: silver is used in
Chemical properties
Like other precious metals, silver is largely "noble" and unreactive with such things as water and oxygen in the air, though it's the most reactive of the precious metals with such things as nitric and sulfuric acid. One thing silver does react with readily is sulfur, forming silver sulfide. This is the blackish gray coating that forms on silver ornaments, crockery, and mirrors we refer to as "tarnish." (It's often noted that eggs tarnish silver cutlery extremely quickly because of the sulfur compounds their proteins contain.)
Silver alloys
Pure silver is too soft for most everyday purposes so it's combined
with other metals (typically
Photo: Hit ordinary silver with a hammer and it squashes. Hit a compound made from silicon and germanium and it shatters into dust (left). But make an intermetallic compound from silver and yttrium and you get a super-hard metal that will withstand repeated hammer blows (right). Intermetallic compounds are broadly similar to alloys and have superior physical, chemical, electrical, and
What is silver used for?
Chart: Where does all the world's silver go? This chart shows figures for 2016–2019, from the inner ring (2016) to the outer one (2019). Source: US Geological Survey, Mineral Commodity Summaries, 2017, 2018, 2019, and 2020.
The answer to why we use any material always lies in its physical
and chemical properties. Looking at what's special, useful, or unusual
about a material always helps us understand why people have used it in
the past (or how they might use it in future). This is the basic idea
behind
The thing we think of first about silver (its attractive shiny
surface) explains why it's so widely used in coins, cutlery, and
jewelry. Shininess also makes silver a perfect material for precise,
scientific
Photo: Old-fashioned photographic film like this uses silver-based chemicals to capture images of the world. It takes quite an effort to turn film back into a printed picture and most people now prefer to use digital cameras instead. That's why there's been a huge decline in the use of silver in photography: in 2017, only 6 percent of the silver used in the United States found its way into photographic applications, down from 50 percent in 1995. Source: US Geological Survey, Mineral Commodity Summaries, January 2017 and January 1996.
Since silver is a good conductor of
Being unreactive, silver and its compounds find important uses in wound-care bandages.
Also in medicine, various silver compounds (including silver nitrates) work as strong
antiseptics and anti-bacterial agents, though silver has largely
been superseded in joint replacements by
