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.
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.
|Mineral||Major Elements||Percentage of Crust|
|Plagioclase Feldspar||O, Si, Al, Ca, Na||39%|
|Alkali Feldspar||O, Si, Al, Na, K||12%|
|Pyroxene||O, Si, Mg, Fe||11%|
|Amphibole||O, Si, Mg, Fe||5%|
|Micas||O, Si, Al, Mg, Fe, Ca, Na, K||5%|
|Clay Minerals||O, Si, Al, Mg, Fe, Ca, Na, K||5%|
|Other Silicates||O, Si||3%|
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.
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.
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.
The Critical Minerals to China, EU, and U.S. National Security
Ten materials, including cobalt, lithium, graphite, and rare earths, are deemed critical by all three.
The Critical Minerals to China, EU, and U.S. Security
Governments formulate lists of critical minerals according to their industrial requirements and strategic evaluations of supply risks.
Over the last decade, minerals like nickel, copper, and lithium have been on these lists and deemed essential for clean technologies like EV batteries and solar and wind power.
What are Critical Minerals?
There is no universally accepted definition of critical minerals. Countries and regions maintain lists that mirror current technology requirements and supply and demand dynamics, among other factors.
These lists are also constantly changing. For example, the EU’s first critical minerals list in 2011 featured only 14 raw materials. In contrast, the 2023 version identified 34 raw materials as critical.
One thing countries share, however, is the concern that a lack of minerals could slow down the energy transition.
With most countries committed to reducing greenhouse gas emissions, the total mineral demand from clean energy technologies is expected to double by 2040.
U.S. and EU Seek to Reduce Import Reliance on Critical Minerals
Ten materials feature on critical material lists of both the U.S., the EU, and China, including cobalt, lithium, graphite, and rare earths.
|Mineral / Considered Critical||🇺🇸 U.S.||🇪🇺 EU||🇨🇳 China|
Despite having most of the same materials found in the U.S. or China’s list, the European list is the only one to include phosphate rock. The region has limited phosphate resources (only produced in Finland) and largely depends on imports of the material essential for manufacturing fertilizers.
Coking coal is also only on the EU list. The material is used in the manufacture of pig iron and steel. Production is currently dominated by China (58%), followed by Australia (17%), Russia (7%), and the U.S. (7%).
The U.S. has also sought to reduce its reliance on imports. Today, the country is 100% import-dependent on manganese and graphite and 76% on cobalt.
After decades of sourcing materials from other countries, the U.S. local production of raw materials has become extremely limited. For instance, there is only one operating nickel mine (primary) in the country, the Eagle Mine in Michigan. Likewise, the country only hosts one lithium source in Nevada, the Silver Peak Mine.
Despite being the world’s biggest carbon polluter, China is the largest producer of most of the world’s critical minerals for the green revolution.
China produces 60% of all rare earth elements used as components in high-technology devices, including smartphones and computers. The country also has a 13% share of the lithium production market. In addition, it refines around 35% of the world’s nickel, 58% of lithium, and 70% of cobalt.
Among some of the unique materials on China’s list is gold. Although gold is used on a smaller scale in technology, China has sought gold for economic and geopolitical factors, mainly to diversify its foreign exchange reserves, which rely heavily on the U.S. dollar.
Analysts estimate China has bought a record 400 tonnes of gold in recent years.
China has also slated uranium as a critical mineral. The Chinese government has stated it intends to become self-sufficient in nuclear power plant capacity and fuel production for those plants.
According to the World Nuclear Association, China aims to produce one-third of its uranium domestically.
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