60 Fun Facts About Iron

What is the chemical symbol for iron?

It comes from the Latin word ferrum.

What is the atomic number of iron?

It sits in group 8 of the periodic table, in the first transition series.

By mass, iron is the most common element where?

Most of it lies in the planet's inner and outer core.

Iron ranks where among elements in the Earth's crust by abundance?

Only oxygen, silicon and aluminium are more abundant in the crust.

What is the common name for the hydrated iron oxides formed when iron meets oxygen and water?

Unlike protective oxides on some metals, rust flakes off and exposes fresh metal to further corrosion.

Why does rusting keep eating into iron instead of stopping at the surface?

Some other metals form thin passivating oxide layers that seal the surface instead.

Below what temperature, its Curie point, does iron become ferromagnetic?

Above that temperature the atomic spins no longer align and iron is only paramagnetic.

At what temperature does iron melt?

On cooling it first crystallises as the body-centred cubic delta allotrope.

Which naturally magnetised iron mineral provided the earliest compasses?

Magnetite particles later coated magnetic tapes and floppy disks.

How many stable isotopes does iron have?

Iron-56 makes up nearly 92 percent of natural iron.

Iron's abundance on rocky planets is due to its production during which cosmic events?

Runaway fusion in these explosions scatters iron into space.

What is believed to generate Earth's magnetic field?

The inner and outer core together make up about 35 percent of Earth's mass.

Roughly how much iron does an adult human body contain?

About three quarters of it is in hemoglobin.

Which iron-containing protein carries oxygen in red blood cells and gives them their colour?

Each molecule can carry up to four oxygen molecules.

Which protein carries absorbed iron through the blood to cells?

At the bone marrow the iron is stored as ferritin before going into hemoglobin.

Why is carbon monoxide poisonous?

The resulting compound is called carboxyhemoglobin.

Which nutrient's deficiency is the most common in the world?

Left untreated it leads to anemia; children and pre-menopausal women are most at risk.

Roughly how many people were affected by the anemia caused by this deficiency in 2015?

A craving to eat ice, called pagophagia, is one of its more specific symptoms.

What is the medical name for the genetic iron-overload disorder?

It stems from abnormally low levels of hepcidin, the regulator of iron entering the bloodstream.

Which chelating drug is used to bind and expel excess iron in cases of iron poisoning?

Sixty milligrams of iron per kilogram of body weight is considered a lethal dose.

Sea mussels use iron-based bonds in their cuticles to do what?

Synthetic replicas showed iron raised the material's toughness 92 times.

The 7.5% nickel in the Gerzeh iron beads (Egypt, 3500 BC or earlier) is the signature of what?

Crustal iron generally has only minuscule nickel impurities.

A dagger forged from a fallen meteorite was found in whose tomb?

Its iron, cobalt and nickel matched a meteorite found in the area.

Which Anatolian people appear to have been the first to master smelting iron from its ores?

The practice spread across the Near East after their empire fell around 1180 BC.

Roughly what temperature must a furnace reach to extract usable metal from iron ore?

That is about 500 degrees hotter than is needed to smelt copper, which is why iron came later.

The Iron Age began when iron tools displaced alloys of which metal?

In some regions the transition from the Bronze Age happened only around 1200 BC.

In which country was cast iron first produced, in the 5th century BC?

It was hardly seen in Europe until the medieval period.

What defines cast iron chemically?

Iron alloys with lower carbon content are called steel.

How much carbon does wrought iron contain?

Its fibrous slag inclusions come from hot rolling the never-fully-molten metal.

Who established a coke-fired blast furnace in 1709, replacing charcoal?

Cheap iron soon went into rails, ships and steam engine cylinders.

Who patented the puddling process for refining iron in 1783?

Joseph Hall and others later improved it.

In which year was the world's first iron bridge built?

It still stands as a monument to iron's role in the Industrial Revolution.

Which inventor's late-1850s process blew air through molten pig iron to make cheap mild steel?

It made steel so economical that wrought iron stopped being made in quantity.

Blacksmiths in Luristan were making good steel by 1000 BC. In which modern country is Luristan?

Wootz steel from India and Damascus steel followed centuries later.

Which chemist made hydrogen from steam and hot iron in 1774, showing conservation of mass?

His work helped turn chemistry into a quantitative science.

Which Prussian king commissioned the first Iron Cross in 1813?

Citizens were urged to swap gold jewellery for iron with the slogan I gave gold for iron.

Roughly what share of worldwide metal production is iron?

Pure iron is soft, so it is usually alloyed into steel.

Which two iron oxide minerals are the major ores of iron?

Siderite, an iron carbonate, is a third important ore.

Which two countries dominate the seaborne iron ore trade with 72 percent of the market?

The Brazilian miner Vale is the world's largest producer, followed by Rio Tinto and BHP.

Banded iron formations, mined as taconite in North America, occur exclusively in rocks from which era?

They contain more than 15 percent iron in thin beds of iron minerals and silica.

What is the largest known meteorite on Earth, an iron mass lying in Namibia?

All the largest known meteorites are made of iron.

The Inuit of Greenland made tools from which meteorite before iron smelting reached them?

About one meteorite in twenty is made of the iron-nickel minerals taenite and kamacite.

Which Indian ruler is credited with erecting the famously rust-resistant iron pillar now in Delhi?

It stands 7.21 metres tall and weighs more than six tonnes.

What gives the Delhi pillar its resistance to corrosion?

The even crystalline layer shields it from the Delhi climate.

How much iron does the human body absorb each day, roughly, despite holding four grams?

The body recycles the iron in its old hemoglobin.

What is the US Tolerable Upper Intake Level for iron for adults?

The Daily Value used on food labels is 18 mg.

Which two elements sit below iron in group 8 of the periodic table?

Iron shares many properties with these heavier group-8 metals.

Which famous pigment is an iron coordination compound?

Ferrocene and ferrioxalate are other iron complexes with industrial or research uses.

What is the range of oxidation states in which iron forms compounds?

The common ones are iron(II) and iron(III).

Which Greek poet's Works and Days named ages of man after gold, silver, bronze and iron?

Ovid later linked the Iron Age with depravity in his Metamorphoses.

Many languages call railways the 'iron road'. Which of these is the German version?

The French, Turkish and Vietnamese words carry the same meaning.

Iron is called the cheapest metal. Roughly what did it cost in the mid-2020s?

Its low cost and high strength make iron alloys the most common industrial metals.

Iron's chemical symbol Fe comes from which Latin word?

The metal belongs to the first transition series and group 8 of the periodic table.

Iron-56 makes up roughly what share of natural iron?

The other stable isotopes are iron-54, iron-57 and iron-58; only iron-57 has a nuclear spin.

What is the half-life of the extinct radionuclide iron-60?

Its granddaughter nickel-60 in meteorites shows iron-60 was present when the Solar System formed.

Which mine in Pará, Brazil, is thought to be the world's largest iron deposit?

Kiirunavaara in Sweden and the Hamersley Basin in Australia are other giant deposits.

Earth's inner and outer cores together make up roughly what share of the planet's mass?

They are thought to be mostly an iron alloy, possibly with nickel.

Wootz steel and Damascus steel were developed around which two dates respectively?

Both were improvements on the steel that Luristan blacksmiths were producing by 1000 BC.

Up to what carbon content does pig iron from a blast furnace contain?

That much carbon makes it weak and brittle; cutting it to 0.002-2.1% produces steel.

Iron working reached Greece from the Near East in which century BC?

From Greece it spread quickly through Europe, while iron appears in China around 700-500 BC.