All About Copper

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Podcast Transcript

When humans first learned how to work with metal, the very first metal they used was copper. 

Copper was easy to shape, easy to find, and relatively abundant. 

Since those early humans began using copper, usage of the metal hasn’t diminished. It’s just that its modern usage is for purposes that the ancient never could have imagined. 

Learn more about copper and its many uses throughout history on this episode of Everything Everywhere Daily.

As I have mentioned before in previous episodes, there were seven metals known in antiquity: gold, silver, lead, tin, iron, mercury, and copper. 

Today is Copper’s turn in the spotlight. 

Of the seven metals that ancient people were aware of, copper was probably the first. If it wasn’t copper, it was probably the much rarer gold or iron from meteorites. 

There are several reasons why copper was probably the first metal. First, unlike most metals, copper can be found in its native form, similar to gold. While it can be found in oxides and other compounds, it is possible to find pure copper.

Second, is that copper is very malleable and has a low melting point. That meant that early humans could take a hunk of copper ore and beat it into something even without the use of fire.

If you remember back to my episode on the three-ages system for ancient history, many historians broadly categorize ancient history into the stone, bronze, and iron ages. 

However, there is an argument to be made that there should be a copper age as well. The copper age is sometimes used, and it is known as the Chalcolithic Era.

The first evidence of copper working dates back about 11,000 years in the Middle East. The oldest known copper object dates back to 8,700 BC, and it was found in Northern Iraq.

The first evidence of copper smelting dates back about 5000 years. Copper smelting appears to have been independently discovered in many places around the world. Copper smelting appeared in China, Mesoamerica, and West Africa.

Ötzi the Iceman, a 5000-year-old man who was found on a glacier, had an axe head made out of almost pure copper.  North American Indians were mining copper in Wisconsin and Michigan at least 8000 years ago.

So, suffice it to say that copper working could be found all over the Earth, at least as far back as the advent of agriculture.

Copper tools were indeed a huge advancement, but they had drawbacks. Because copper was so soft and malleable, copper tools were easily damaged when used. A copper axe would quickly lose its edge and develop nicks in its blade. A copper axe or saw was certainly better than nothing, but they were hardly ideal.

The big advancement in copper came when it was used with tin to make an alloy called bronze. 

I’ve already discussed bronze in-depth in my episode on tin, so I’m not going to spend more time on it here, but suffice it to say that bronze was a big advancement over copper. 

As bronze and, later, iron became dominant, the use of copper changed from tools to jewelry, utensils, cookware, and, most importantly, coinage. 

Gold and silver were preferred for use in coinage, but there was a problem. For small transactions, it wasn’t possible to make a coin small enough to have the proper amount of value.

That is where copper came in. Copper was much more abundant and was used for small-value coins. 

The oldest copper coins that have been discovered date back to the third century BC. These coins were issued by Greek rulers in Bactria, today parts of Iran and Afghanistan, in the aftermath of Alexander the Great.

These earliest coins were an alloy of copper and nickel.

The Romans issued small denomination coins known as an as. These coins were made out of bronze or copper at different points in history. 

Because it was primarily used for money, in addition to other uses such as plumbing, the Romans had a huge appetite for copper. Their biggest copper mines were on the island of Cyprus.

The metal in Latin was known as aes cyprium, which simply meant “metal of Cyprus”, but it was later changed to just cuprum. Cuprum eventually became copper in English, and it is why the abbreviation for the element on the Periodic Table is Cu.

At its peak, the Romans were producing 15,000 tons of copper per year throughout the empire. 

The Roman use of copper and copper-based alloys for small coins is still practiced by most countries around the world today. If you come across a copper-looking coin, it probably isn’t worth too much. 

For the next several hundred years, the uses for copper remained pretty much the same. It was used for art, ornaments, and coins. 

It was still a very important metal. 

One of the most important sources of copper in the Middle Ages was the copper mine in Falun, Sweden. The mine supplied ? of all the copper in Europe for centuries, and it was the biggest source of revenue for the Swedish crown. Many of the wars fought by Sweden in the 17th century were funded by the copper mine in Falun. 

On a personal note, I’ve visited the Falun mine, which is today a UNESCO World Heritage Site. It is a fascinating place to visit to see how mining was once conducted. It is located about 200 kilometers northwest of Stockholm, and I highly recommend visiting if you are ever in the area. 

Before I move on to how the human consumption of copper has changed, let me go over some of the basic facts about copper. 

Copper is the 29th element on the periodic table, between nickel and Zinc.

It is also in the 11th group or column on the table, along with silver and gold.  Copper is the only metal other than gold, which doesn’t have a silvery/grey color. 

There are two properties that were not well known to the ancients that you are probably very familiar with and are probably the first things you think of when you think of copper. Heat and electrical conductivity. 

Copper is not the best conductor of heat and electricity. Silver is better than copper at both, but not that much greater. 

These properties of copper made it extremely valuable with the advent of the Industrial Revolution. 

Almost as soon as scientists began experimenting with electricity the found that copper was an excellent conductor. Electricity could flow through copper with very little resistance. 

In the late 19th century, as the world began becoming electrified, the demand for copper skyrocketed. It wasn’t just ornamental anymore. Copper became a vital strategic resource. 

Copper wires were stretched across thousands of miles to create a network of telegraph terminals. 

Vast quantities of copper were needed for electrical wires that were stretched from power stations to cities. Within cities, copper wiring could be seen connecting buildings strung together on poles above street level. 

It wasn’t just wiring to transmit electricity that was needed. Almost every electrical device requires copper. Electrical motors required copper for their electromagnets and brushes. Switches would have copper, as did most lightbulbs. 

When telephones were invented, it required even more copper wiring. 

Automobiles eventually required copper writing as well. They were a vital part of the generator and the electrical systems of cars. 

With the advent of cable television, copper-based coaxial cable required more copper wiring, and over course computers and the internet created the need for computer cables like category-5, USB, and a host of other cables. 

Today, electrical writing is responsible for 60% of the total world demand for copper.  

Most of you are probably familiar with the electrical properties of copper, so I won’t spend more time on it, but copper does have some other amazing properties as well. 

As I mentioned before, copper is a great conductor of heat. Copper is the preferred material for heat sinks for computer processors. Copper heat sinks are placed on hot processors. The heat sink can transfer the heat away from the processor, where it can be dissipated. 

Copper’s heat-conducting ability makes it commonplace in car radiators and refrigerators.

The heat-conducting properties of copper also make it a choice for cookware for some cooks. Because it distributes heat so well, heat is evenly distributed throughout the pot, avoiding spots that are hotter than others. 

Conducting electricity and heat aren’t the only properties of copper that have been taken advantage of in the modern world.

Copper is also highly resistant to corrosion. 

If you have ever seen a building built in the 19th or early 20th centuries, you might have noticed a green roof. Odds are the roof it made out of copper. 

When copper is exposed to air, it will oxidize and form a thin layer of copper oxide known as a patina.  This patina, which is usually only about a tenth of a millimeter thick, serves as a protective layer on the copper.

The skin of the Statue of Liberty is made out of copper, and its light green hue is due to its patina. 

This corrosion resistance is what makes copper a good choice for spires, rain gutters, and some old doors. 

The benefits of copper get even better. Copper is considered to be a biostatic substance. This means that it is very difficult for anything living to grow on it. 

18th-century sailing ships used copper to line their hulls as it would prevent the growth of barnacle, which would slow down ships. 

Likewise, the interior of water tanks in ships were often lined with copper to prevent the growth of harmful agents. 

…this brings me to what is perhaps the feature of copper that might prove to be the most important going forward. Copper is antibacterial. 

Surfaces that are coated in copper have been shown to kill 99.9% of disease-carrying microbes. 

Because hospitals are major vectors for the transmission of diseases, there have been calls to replace many of the fixtures in hospitals, such as door knobs, sinks, faucets, handrails, and other things that people touch, with copper. 

Hospitals in many countries around the world are starting to install copper or copper alloys like brass to prevent the spread of disease.

The reason why copper is antimicrobial is due to something called the oligodynamic effect. The oligodynamic effect is when ions of heavy metals like copper disrupt cellular processes. 

While copper prevents growth on its surface, that doesn’t mean it is inimicable to life.  

Copper is actually an essential trace element for almost all plants and animals. 

The recommended daily allowance of copper for an adult human is about 1400 micrograms. 

Foods that are good dietary sources of copper include oysters, liver, and some mushrooms. 

Symptoms of copper deficiency include tiredness and weakness, anemia, vision loss, memory issues, and sensitivity to cold. 

Before you start eating pennies to get your copper, realize that you can also get copper toxicity. Copper toxicity is pretty rare, but it can happen.

In a very real way, copper is the backbone of our modern civilization.  The internet and everything electrical involve copper. The device that you are using to listen to these words right now probably has some copper in it.

Copper is a pretty amazing substance. Despite being one of the oldest metals that humans ever worked with, we are using more copper than ever today.