Oxygen
Oxygen is the most abundant element in the Earth’s crust, accounting for approximately 467,100 parts per million, or 46.6%. It primarily exists as a key component of silicate minerals, where it bonds with other elements. Additionally, oxygen is found in various compounds such as carbonates and phosphates. This versatile element is utilized across industrial, medical, and commercial sectors; for example, it is used in conjunction with acetylene for cutting and welding metals, in hospitals to alleviate respiratory conditions, and in the manufacturing of explosives, among other applications.
Silicon
Silicon ranks as the second most prevalent element in the Earth’s crust, representing about 267,900 parts per million, equivalent to 27.7%. In the crust, silicon primarily associates with oxygen to form silicate minerals and sand. It can be extracted from materials such as quartzite, mica, and talc. Silicone, derived from silicon, is commonly used in hydraulic fluids, electrical insulators, lubricants, and more. Solid silicon serves a crucial role in computer technology as a semiconductor, as well as in the production of transistors for the electronics industry, aluminum, alloys, ceramics, glass, pesticides, cosmetics, and pharmaceuticals.
Aluminum
Aluminum is the third most abundant element in the Earth’s crust, comprising roughly 80,700 parts per million or 8.1%. Unlike some elements, aluminum does not occur freely in nature; it is typically found in compound forms such as aluminum oxide, aluminum hydroxide, and potash alum. The extraction of aluminum from its compounds largely occurs through the Bayer and Hall-Héroult processes. This element is favored for its lightweight properties and is extensively utilized in the production of foil, packaging materials, machine components, spacecraft, and automotive parts.
Iron
Iron constitutes around 50,500 parts per million, or 5% of the Earth’s crust, existing in ores such as hematite and magnetite. It has a wide range of applications, particularly in steel production. Iron is also used for crafting cookware, cast iron, and wrought iron, which are essential in various industries. The element is characterized by its shiny gray surface and its tendency to oxidize when exposed to air, resulting in rust, commonly known as hydrated iron oxide.
Calcium
Calcium makes up over 4% of the Earth’s crust and is recognized for its non-reactive nature, easily forming compounds with oxygen and water. Calcium compounds find utility in diverse applications, including gypsum boards, toothpaste, and chalk.
Sodium
Sodium constitutes more than 2% of the Earth’s crust and does not exist freely due to its high reactivity. The most recognized application of sodium is in table salt, or sodium chloride. It is present in various useful compounds, including baking soda, caustic soda, and borax. Sodium lamps are widely used for street lighting and in parking lots.
Magnesium
Magnesium accounts for over 2% of the Earth’s crust and is not found freely in nature; instead, it occurs in various other compounds. This versatile element is applied in both industrial and domestic settings. It is a primary component of Epsom salts and is utilized as an antacid and laxative. Magnesium-aluminum alloys are particularly valuable in airplane construction and other applications requiring strong yet lightweight metals.
Potassium
Potassium makes up about 2% of the Earth’s crust and does not occur naturally in its pure form. It is essential for forming several beneficial compounds used in manufacturing fertilizers, soaps, detergents, and certain types of glass.
Other Elements Found in the Earth’s Crust
The Earth’s crust also contains several other elements, including:
- Titanium: 0.44%
- Hydrogen: 0.14%
- Phosphorus: 0.12%
- Manganese: 0.10%
- Fluorine: 0.08%