Visualizing the Scale and Composition of the Earth's Crust
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Visualizing the Scale and Composition of the Earth’s Crust

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Visualizing the Scale and Composition of the Earth’s Crust

For as long as humans have been wandering the top of Earth’s crust, we’ve been fascinated with what’s inside.

And Earth’s composition has been vital for our advancement. From finding the right kinds of rocks to make tools, all the way to making efficient batteries and circuit boards, we rely on minerals in Earth’s crust to fuel innovation and technology.

This animation by Dr. James O’Donoghue, a planetary researcher at the Japan Aerospace Exploration Agency (JAXA) and NASA, is a visual comparison of Earth’s outer layers and their major constituents by mass.

What is the Composition of Earth’s Crust?

The combined mass of Earth’s surface water and crust, the stiff outermost layer of our planet, is less than half a percent of the total mass of the Earth.

There are over 90 elements found in Earth’s crust. But only a small handful make up the majority of rocks, minerals, soil, and water we interact with daily.

1. Silicon

Most abundant in the crust is silicon dioxide (SiO2), found in pure form as the mineral quartz. We use quartz in the manufacturing of glass, electronics, and abrasives.

Why is silicon dioxide so abundant? It can easily combine with other elements to form “silicates,” a group of minerals that make up over 90% of Earth’s crust.

Clay is one of the better-known silicates and micas are silicate minerals used in paints and cosmetics to make them sparkle and shimmer.

MineralMajor ElementsPercentage of Crust
Plagioclase FeldsparO, Si, Al, Ca, Na39%
Alkali FeldsparO, Si, Al, Na, K12%
QuartzO, Si12%
PyroxeneO, Si, Mg, Fe11%
AmphiboleO, Si, Mg, Fe5%
Non-silicatesVariable8%
MicasO, Si, Al, Mg, Fe, Ca, Na, K5%
Clay MineralsO, Si, Al, Mg, Fe, Ca, Na, K5%
Other SilicatesO, Si3%

2. Aluminum and Calcium

SiO2 bonds very easily with aluminum and calcium, our next most abundant constituents. Together with some sodium and potassium, they form feldspar, a mineral that makes up 41% of rocks on Earth’s surface.

While you may not have heard of feldspar, you use it every day; it’s an important ingredient in ceramics and it lowers the melting point of glass, making it cheaper and easier to produce screens, windows, and drinking glasses.

3. Iron and Magnesium

Iron and magnesium each make up just under 5% of the crust’s mass, but they combine with SiO2 and other elements to form pyroxenes and amphiboles. These two important mineral groups constitute around 16% of crustal rocks.

Maybe the best known of these minerals are the two varieties of jade, jadeite (pyroxene) and nephrite (amphibole). Jade minerals have been prized for their beauty for centuries, and are commonly used in counter-tops, construction, and landscaping.

Some asbestos minerals, now largely banned for their cancer-causing properties, belong to the amphibole mineral group. They were once in high demand for their insulating and fire-retardant properties and were even used in brake pads, cigarette filters, and as artificial snow.

4. Water

Surprisingly, even though it covers almost three quarters of Earth’s surface, water (H2O) makes up less than 5% of the crust’s mass. This is partly because water is significantly less dense than other crustal constituents, meaning it has less mass per volume.

Breaking Earth’s Crust Down by Element

Though there are many different components that form the Earth’s crust, all of the above notably include oxygen.

When breaking down the crust by element, oxygen is indeed the most abundant element at just under half the mass of Earth’s crust. It is followed by silicon, aluminum, iron, calcium, and sodium.

All other remaining elements make up just over 5% of the crust’s mass. But that small section includes all the metals and rare earth elements that we use in construction and technology, which is why discovering and economically extracting them is so crucial.

What Lies Below?

As the crust is only the outermost layer of Earth, there are other layers left to contemplate and discover. While we have never directly interacted with the Earth’s mantle or core, we do know quite a bit about their structure and composition thanks to seismic tomography.

The Upper Mantle

At a few specific spots on Earth, volcanic eruptions and earthquakes have been strong enough to expose pieces of the upper mantle, which are also made of mostly silicates.

The mineral olivine makes up about 55% of the upper mantle composition and causes its greenish color. Pyroxene comes in second at 35%, and calcium-rich feldspar and other calcium and aluminum silicates make up between 5–10%.

Going Even Deeper

Beyond the upper mantle, Earth’s composition is not as well known.

Deep-mantle minerals have only been found on Earth’s surface as components of extra-terrestrial meteorites and as part of diamonds brought up from the deep mantle.

One thing the lower mantle is thought to contain is the silicate mineral bridgmanite, at an abundance of up to 75%. Earth’s core, meanwhile, is believed to be made up of iron and nickel with small amounts of oxygen, silicon, and sulphur.

As technology improves, we will be able to discover more about the mineral and elemental makeup of the Earth and have an even better understanding of the place we all call home.

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This article was published as a part of Visual Capitalist's Creator Program, which features data-driven visuals from some of our favorite Creators around the world.

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Energy

Visualizing U.S. Consumption of Fuel and Materials per Capita

Wealthy countries consume large amounts of natural resources per capita, and the U.S. is no exception. See how much is used per person.

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Visualizing U.S. Consumption of Fuel and Materials per Capita

This was originally posted on Elements. Sign up to the free mailing list to get beautiful visualizations on natural resource megatrends in your email every week.

Wealthy countries consume massive amounts of natural resources per capita, and the United States is no exception.

According to data from the National Mining Association, each American needs more than 39,000 pounds (17,700 kg) of minerals and fossil fuels annually to maintain their standard of living.

Materials We Need to Build

Every building around us and every sidewalk we walk on is made of sand, steel, and cement.

As a result, these materials lead consumption per capita in the United States. On average, each person in America drives the demand of over 10,000 lbs of stone and around 7,000 lbs of sand and gravel per year.

Material/Fossil FuelPounds Per Person
Stone10,643
Natural Gas9,456
Sand, Gravel7,088
Petroleum Products 6,527
Coal 3,290
Cement724
Other Nonmetals569
Salt359
Iron Ore239
Phosphate Rock 166
Sulfur66
Potash49
Soda Ash36
Bauxite (Aluminum)24
Other Metals 21
Copper13
Lead11
Zinc6
Manganese4
Total 39,291

The construction industry is a major contributor to the U.S. economy.

Crushed stone, sand, gravel, and other construction aggregates represent half of the industrial minerals produced in the country, resulting in $29 billion in revenue per year.

Also on the list are crucial hard metals such as copper, aluminum, iron ore, and of course many rarer metals used in smaller quantities each year. These rarer metals can make a big economic difference even when their uses are more concentrated and isolated—for example, palladium (primarily used in catalytic converters) costs $54 million per tonne.

Fuels Powering our Lives

Despite ongoing efforts to fight climate change and reduce carbon emissions, each person in the U.S. uses over 19,000 lbs of fossil fuels per year.

U.S. primary energy consumption by energy source, 2021

Gasoline is the most consumed petroleum product in the United States.

In 2021, finished motor gasoline consumption averaged about 369 million gallons per day, equal to about 44% of total U.S. petroleum use. Distillate fuel oil (20%), hydrocarbon gas liquids (17%), and jet fuel (7%) were the next most important uses.

Reliance on Other Countries

Over the past three decades, the United States has become reliant on foreign sources to meet domestic demand for minerals and fossil fuels. Today, the country is 100% import-reliant for 17 mineral commodities and at least 50% for 30 others.

In order to reduce the dependency on other countries, namely China, the Biden administration has been working to diversify supply chains in critical minerals. This includes strengthening alliances with other countries such as Australia, India, and Japan.

However, questions still remain about how soon these policies can make an impact, and the degree to which they can ultimately help localize and diversify supply chains.

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