What Is the Most Abundant Element on Earth? Not Carbon

Think of Earth's crust as the planet's outermost skin: a thin layer packed with common elements to form the foundation of silicate minerals and rocks. The chemical composition here is different from what's deeper inside, like the Earth's mantle or core.

These are just a few elements Earth's crust comprises, ranked by the percent of the weight they occupy.

1. Oxygen (46%)

Oxygen reigns supreme in the Earth's crust, accounting for nearly half its total mass. It also obviously plays a major part in the human body's chemical composition.

While you might think of oxygen as the gas you breathe, here it's busy forming oxides and partnering with other common elements like silicon. Oxygen is crucial in silicate minerals like quartz (silicon dioxide) and feldspar.

2. Silicon (27%)

The second-most abundant element in the crust is silicon, famous for making silicon chips and quartz crystals.

Silicon loves to form compounds, especially silicon dioxide, found in everything from metamorphic rocks to beach sand. Its ability to link up with oxygen creates structures vital to life on Earth.

3. Aluminum (8%)

Say hello to aluminum, the third-most abundant element in the crust. Despite being lightweight, aluminum packs a punch as a common element in crustal abundance, appearing in minerals like bauxite and feldspar.

It's a big player in the construction of common oxides and essential to industries worldwide.

4. Iron (5%)

Iron isn't just a major component of Earth's core; it also hangs out in the crust, forming oxides like hematite and magnetite. These compounds give soil its reddish hue and make up a significant portion of metamorphic rocks.

Fun fact: Iron accounts for much of the weight of Earth's magnetic field!

5. Calcium (4%)

The No. 5 spot goes to calcium, which forms common minerals like calcite and gypsum. As a vital part of limestone, it plays a starring role in Earth's natural beauty, from towering cliffs to coral reefs. Plus, calcium is an essential nutrient for both plants and humans.

Let's head up into Earth's atmosphere, where a different mix of elements dominates. These gases are not only breathable but also shape our planet's climate and weather.

We've ranked them by the percent of the atmosphere they occupy.

1. Nitrogen (78%)

The heavyweight champion of the Earth's atmosphere is nitrogen. This major component is relatively inert, meaning it doesn't react easily — a good thing for maintaining a stable atmosphere. Nitrogen is essential for life as it forms a key part of proteins and DNA.

2. Oxygen (21%)

Here's a familiar face! Oxygen is the second-most abundant element in the atmosphere. Unlike its role in the crust, atmospheric oxygen exists mostly as O₂, fueling respiration in animals and combustion processes.

3. Argon (0.93%)

This noble gas takes third place, despite existing in only trace amounts. Argon's inert nature makes it perfect for preserving documents and filling lightbulbs. It might not be flashy, but it's an essential part of the atmosphere's chemical composition.

4. Carbon Dioxide (0.04%)

Though present in a small fraction, carbon dioxide punches above its weight in importance. It's a major component of photosynthesis and a significant contributor to Earth's greenhouse effect. CO₂ plays a pivotal role in regulating the planet's temperature.

5. Neon (0.0018%)

Rounding out the top five is neon, the element that makes your favorite signs glow. Like argon, neon exists in trace amounts, but it's a superstar in its own right, adding to the diversity of common elements in the atmosphere.

Now, let's zoom out to other elements common throughout the cosmos. When we look at the entire Earth in the context of the universe, the mix of elements shifts dramatically. Space is dominated by light, simple elements formed in the aftermath of the Big Bang.

We've ranked them by the percent of the universe's mass that they occupy.

1. Hydrogen (75%)

Hydrogen is the most abundant element in the universe by far. This lightweight element is the building block of stars and galaxies. It's the simplest element, consisting of just one proton and one electron, yet it powers the sun through nuclear fusion. Talk about high temperatures!

2. Helium (24%)

The runner-up in the cosmic race is helium, another product of the Big Bang. Helium is a highly reactive element in stars, where it helps drive the fusion process that lights up the universe. While rare on Earth, helium dominates space.

3. Oxygen (1%)

Oxygen makes another appearance here, ranking as the third-most abundant element in the universe. It forms water and oxides across planets and moons, showcasing its versatility in both liquid and solid forms.

4. Carbon (0.5%)

Carbon, the backbone of organic life, is the fourth-most abundant element out there. This versatile element forms the basis of complex molecules, from amino acids to the graphite in your pencil. Its abundance makes life as we know it possible.

5. Neon (0.1%)

Neon strikes again! This noble gas is common in the universe, particularly in the outer layers of stars. Its vibrant glow is a small but vital part of cosmic diversity.

We created this article in conjunction with AI technology, then made sure it was fact-checked and edited by a HowStuffWorks editor.