What is Iron?

What is Iron?

Iron ore in rock form
iron ore on a rocky base

Did you know that iron is a healthy nutrient for our bodies as well as the main ingredient in the manufacture of steel?

Before we venture into the types of iron, let’s first examine its properties. Iron is a mineral with the symbol Fe and atomic number 26.

On the periodic table, it belongs to the first transition series, which reflects a change in the inner layer of electrons, but we’ll leave that for the chemists since the chemical compound of this mineral is beyond the scope of this article.

Iron is the most common element on Earth when referenced by mass and is very prominently found in the Earth’s outer and inner cores. It is the fourth most common element in the Earth’s crust, but the process to extract it requires kilns or furnaces capable of reaching a temperature of 2,730 °F or higher.

A Little Bit of Iron History

Bronz Statue
Bronze Statue
Wikipedia_Public Domain

The Bronze Age (c. 3300–1200 BC) is characterized by the use of bronze as the metal of choice to create art, tools, and weapons. It was the first time metals were used for these purposes. Prior to this period, stone was used as a tool and for weapons; hence, the Stone Age.

Interestingly enough, the Bronze Age also brought us the first writing system and the invention of the wheel. An intriguing period of creative thought for sure.

Enter Iron

Say goodbye to bronze and hello to iron; hence, the Iron Age, which started around 1200 BC. It should be noted that before the Iron Age was coined, there were occasions when iron was found to be used much earlier.

One historical account was that of the ancient Egyptians. Archeologists found iron beads made from meteorites dating back to 3200 B.C.  Iron is abundant in outer space. But these incidences were rare until the time when iron became the metal of choice.

Iron for Infrastructure

Steel Columns and beams of 1 World Trade Center
Steel  (an alloy of iron) columns and beams of 1 World Trade Center Under Construction. Photo: SS

Once we entered the 19th century, new uses for iron materialized. It was discovered that this mineral, when mixed with carbon, can be used for building purposes, and with the advent of the industrial revolution, where items were being mass-produced, the manufacture of iron became an economical commodity. 

Building Construction

Iron in its pure form is not used for building construction since it would not have the tensile or compressive strength required for infrastructure, but when other elements are added to it, such as carbon, it can become a desirable metal for constructing bridges and buildings, since its tensile and compression strengths are bolstered. Let’s take a look at iron alloys.

Cast Iron

Cast iron has 2 to 4% of carbon mixed in with it along with some small amounts of impurities, such as sulfur and phosphorus. This alloy has an advantage as it is simple to cast (mold). Therefore, cast iron is an excellent choice for decorative ironwork on structures like fencing and benches.  

A good example of the use of cast iron can be found in the SoHo and nearby areas of New York City. There are about 250 cast iron buildings located there. The initial purpose of cast iron facades was to improve older buildings, but they were eventually used in newer construction as well. 

Cast iron fence. Palermo Italy
Cast iron fence. Palermo Italy. Photo SS
Cast Iron’s Disadvantage

Because of iron’s brittleness (subject to fractures under stress) and relatively low tensile (ability to stretch) strength, cast iron is not a suitable material for products that require a high degree of tension or bending moments.

Cast Iron’s Advantage
Cast iron buildings NYC
Cast iron buildings, Lower Manhattan. Photo: SS

Although tension is not a good quality of cast iron, it does have acceptable compressive strength (ability to sustain heavy loads) and it is also durable (ability to withstand wear).

Construction of bridges and buildings using cast iron was very popular in the late 19th and early 20th centuries. In fact, there is a whole section in New York City that is called the Cast Iron District, also known as SOHO.

Later in the mid-20th century and on to today’s building construction techniques, cast iron gave way to steel because of the fact that steel has high tension capabilities as well as high compression.

Wrought Iron 

Wrought iron is not an iron alloy. It is made entirely of iron with no  carbon additions. Wrought iron is malleable, ductile, and corrosion-resistant

This metal is different from cast iron and because of its malleability. it was given the name wrought since it could be hammered into shape while it remained hot. Wrought iron is a prerequisite to mild steel, also called low-carbon steel, and is considered the first of the steel alloys.

As a matter of fact, wrought iron was initially refined into steel. In the 1860s, ironclad warships and railways were built with these iron alloys.

Wrought iron was eventually halted to make way for the less expensive and stronger steel, as steel’s advantage over wrought iron and cast iron is its ability to absorb shocks without breaking.

Steel

Steel Cantilever at Chase Bank Headquarters
Steel Cantilever at Chase Bank Headquarters Under Construction. Photo: SS

Steel is an iron alloy that contains a low amount of carbon, roughly 0.40%; however, that is enough to change iron’s characteristics, and with the advent of the Bessemer process, making steel became less costly to create. 

Steel has good tension and compression factors, as well as being impact resistant. Steel is so strong that it is used to cantilever skyscrapers. This is why you see so many buildings under construction today that have steel as their framework.

Iron for Nutrition

Red Blood Cells
“Red blood cells” by rpongsaj is licensed under CC BY 2.0

Since iron is a mineral, it is also an important nutrient for our bodies. If you have an iron deficiency, you may possibly acquire anemia and also fatigue.

So how much iron do you need on a daily basis? For most people, an adequate amount of iron is consumed daily via the foods that we eat, but to determine your specific iron needs, you can see a chart and information here. One person told us that he eats yogurt and raisins every day. Raisins contain a certain amount of iron. 

Do you know why our blood is red?  It is because there is an interaction between iron and oxygen within the blood creating a red color. Learn more about red blood cells and iron here.

To be sure you have enough iron in your body, check with your doctor to confirm you are not deficient.

Conclusion

Besides being an essential component for healthy blood in our bodies, iron became an essential component for weapons and later, building materials.

Numerous bridges and buildings have been constructed during the 18th, 19th, and 20th centuries using iron, but as the industrial revolution advanced and the making of materials became automated, new alloys of iron were created, specifically, steel and along with concrete, led to the construction of stronger buildings, bridges, and skyscrapers we see today all over the world.

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