12 Most Common Minerals on Earth

Minerals are the fundamental components of the Earth's crust, essential to the structure of rocks and the processes that shape our planet. These naturally occurring, inorganic solids possess a specific chemical composition and crystalline structure. While there are thousands of known minerals, only a few are common enough to make up the majority of the Earth's crust. Each mineral has unique properties and plays a vital role in various geological and industrial processes. Here, we explore the most common minerals on Earth, highlighting their characteristics, occurrences, and uses.

Rock-forming Minerals: Most Abundant Minerals

Feldspar

Feldspar minerals: Amazonite, Microcline, Albite, and Orthoclase

Feldspar (Feldspars) are a group of silicate minerals that together make up about 50% of the Earth's crust. These minerals are primarily composed of silicon, oxygen, aluminum, and varying amounts of potassium, sodium, and calcium. They are the most common mineral group and can be found in igneous, metamorphic, and sedimentary rocks. Feldspars are typically classified into two main categories:

Plagioclase Feldspar (~38%) - This subgroup of feldspars is rich in sodium and calcium. Examples include Albite and Anorthite.
K-Feldspar (~12%) - K-feldspars are feldspars rich in potassium. Examples include Orthoclase, Microcline, and Sanidine.

Feldspars exhibit a range of colors, including white, pink, gray, and brown. They are characterized by their hardness (around 6 on the Mohs scale) and their cleavage planes that intersect at nearly right angles. Feldspar minerals have several important uses. They are a key ingredient in the manufacture of ceramics and glass. In ceramics, they act as a flux, lowering the melting temperature of the materials with which they are mixed. Feldspars are also used in the production of glazes, as fillers in various products such as paints and rubber, and as a source of alumina in the manufacture of abrasives and insulation materials.

Quartz

Quartz cluster

Quartz is another silicate mineral composed of silicon dioxide (SiO₂) and is known for its hardness and durability. It makes up about 12% of the Earth's crust. It is the second most abundant mineral in the Earth's crust and is a major component of sand, sandstone, and granite.

Quartz crystallizes in the hexagonal system and is noted for its hardness, ranking 7 on the Mohs scale. Quartz is typically transparent or translucent, but it can come in a variety of colors due to impurities, including purple amethyst, yellow citrine, and pink rose quartz. It exhibits a conchoidal fracture and lacks cleavage, making it durable and resistant to weathering.

Quartz is also piezoelectric, meaning it can generate an electric current when pressure is applied. Quartz is widely used in the production of glass, including optical glass and fiberglass. In the electronics industry, quartz crystals are used in oscillators and frequency control devices.

Pyroxene

Augite - Pyroxene

Pyroxenes are a group of inosilicate minerals that form long, chain-like structures. They are composed of silicon, oxygen, and various other elements, including iron, magnesium, and calcium. This group of silicate minerals makes up about 11% of the Earth's crust. The pyroxene group consists of a range of silicate minerals that are typically dark-colored and found in igneous and metamorphic rocks. They include minerals such as augite, diopside, and hypersthene.

Pyroxenes are characterized by their monoclinic crystal structure, two cleavage planes that intersect at approximately 90 degrees, and hardness ranging from 5 to 7 on the Mohs scale. Pyroxenes have limited economic uses but are important in petrology for understanding rock formations and in the study of planetary geology.

Amphibole

Amphibole (Actinolite)

Amphibole is another group of silicate minerals. This group consists of inosilicate minerals that form double chains of tetrahedra and are typically found in metamorphic and igneous rocks. Amphiboles make up about 5% of the Earth's crust. The most common members of this group are hornblende and tremolite. Amphiboles are characterized by their long, prismatic crystals and two cleavages intersecting at approximately 60° and 120°, which can be seen in their cleavage patterns. Amphiboles generally have a hardness ranging from 5 to 6 on the Mohs scale and can appear in dark colors, often green, brown, or black, and possess a vitreous to dull luster. They have a complex chemical composition that includes silicate, aluminum, iron, and magnesium.

Amphiboles are used in the production of asbestos (although some forms are hazardous), concrete, and roofing materials.

Mica

Mica minerals: Muscovite, Biotite (black)

Micas (Mica Group) are a group of sheet silicate minerals that make up about 5% of the Earth's crust. Mica minerals are known for their perfect basal cleavage, which allows them to be split into thin, flexible sheets. They are commonly found in igneous and metamorphic rocks. The two main types are muscovite, which is light-colored and transparent, and biotite, which is dark-colored and opaque. Their hardness ranges from 2.5 to 3 on the Mohs scale. Micas have a glassy luster and a wide range of colors, from clear to green to brown. Their layered structure gives them excellent flexibility and heat resistance.

Micas have several industrial applications due to their heat resistance, electrical insulating properties, and ability to be easily split into thin sheets. They are used in the production of electrical insulators, paints, and cosmetics.

Clay Minerals

Clay minerals

Clay minerals are a group of hydrous aluminum phyllosilicates. They are formed through the weathering and alteration of feldspars and other silicate minerals. Clay minerals are characterized by their fine particle size, typically less than 2 micrometers in diameter, and their layered crystal structures. They generally have low hardness, typically less than 2.5 on the Mohs scale. Common types of clay minerals include kaolinite, illite, and smectite. While not a single mineral, clay minerals together make up a significant portion of the Earth's crust, estimated to be around 4-5%.

Clay minerals have a sheet-like crystal structure, which imparts them with the ability to absorb and retain water. This makes them crucial in various geological processes, including soil formation and sedimentary rock development. Clay minerals have diverse industrial applications. In ceramics, they are used to make pottery, bricks, and tiles due to their ability to be molded and fired at high temperatures.

Other Silicates

Garnet

Garnet is a group of minerals that includes almandine, pyrope, and spessartine. It is the seventh most abundant mineral in the Earth's crust. Garnets are typically found in metamorphic rocks like schist and gneiss, as well as in some igneous rocks. They are characterized by their hard, glassy appearance, with a hardness of 6.5 to 7.5 on the Mohs scale. Garnets come in a range of colors, including red, green, yellow, and brown, and they often form dodecahedral or trapezohedral crystals. Garnets are used as abrasives in cutting and polishing, as gemstones in jewelry, and in water filtration systems. Their durability also makes them valuable in glass and ceramics production.

Olivine

Olivine, gem quality (peridot)

Olivine is a silicate mineral composed primarily of magnesium and iron silicate with the chemical formula (Mg,Fe)₂SiO₄. It is a significant mineral in the Earth's upper mantle and is commonly found in igneous rocks such as basalt and peridotite, as well as in some metamorphic rocks. Olivine crystallizes in the orthorhombic system, and its crystals are often olive-green to yellowish-green in color, which is where it gets its name. It has a glassy luster and a hardness of 6.5 to 7 on the Mohs scale. Olivine's high-temperature stability and resistance to weathering make it a prevalent component in ultramafic rocks. Olivine is used as a refractory material in steelmaking and foundry applications, in glass production, and can be a gemstone (peridot).

Talc

Talc is a soft, hydrous magnesium silicate mineral with the chemical formula Mg₃Si₄O₁₀(OH)₂. It is the softest mineral on the Mohs scale, with a hardness of 1. Talc is typically found in metamorphic rocks, particularly in regions of ultramafic and metamorphosed sedimentary rocks. It usually appears as a green, gray, white, or colorless mineral with a greasy or soapy feel. Talc has perfect basal cleavage, allowing it to be easily split into thin, flexible sheets. Talc is used in talcum powder, ceramics, and as a filler in paints, rubber, and plastics. Its heat resistance also makes it useful in electrical insulators and as a lubricant.

Non silicates

Calcite

Calcite is a carbonate mineral with the chemical formula CaCO₃. It is one of the most common minerals, making up about 4% of the Earth's crust. Calcite is a major component of sedimentary rocks such as limestone and metamorphic rocks like marble. It crystallizes in the hexagonal system, often forming rhombohedral crystals. Calcite is usually colorless or white but can occur in various colors due to impurities. It has a hardness of 3 on the Mohs scale and is characterized by its ability to effervesce in dilute hydrochloric acid, releasing carbon dioxide gas.

Calcite is extensively used in construction, particularly in the production of cement and lime. It is also employed in the manufacture of glass and ceramics, where it acts as a flux to lower the melting point.

Hematite

Hematite is an iron oxide mineral with the chemical formula Fe₂O₃. It is one of the most common forms of iron ore and is a primary source of iron for steel production. It is often found in sedimentary rocks, such as shales and sandstones, as well as in metamorphic and igneous rocks. Hematite typically appears in shades of red to reddish-brown and has a metallic to earthy luster. It exhibits a hardness of about 5 to 6 on the Mohs scale and has a distinct red streak when powdered. Hematite forms through the oxidation of iron-bearing minerals and is often associated with iron-rich deposits. Hematite is primarily used in the production of iron and steel and as a pigment.

Pyrite

Pyrite, often known as "fool's gold," is a mineral composed of iron sulfide (FeS₂). It is the ninth most abundant mineral in the Earth's crust. Pyrite commonly forms in sedimentary, metamorphic, and igneous rocks and is recognizable by its metallic luster and pale brass-yellow color. It crystallizes in the cubic system, and its crystals often appear as cubes or pyritohedra. Pyrite has a hardness of 6 to 6.5 on the Mohs scale and is brittle, breaking with a conchoidal fracture.

Pyrite is primarily used as a source of sulfur in sulfuric acid production, which is vital for various industrial processes, including fertilizer manufacturing.

Gypsum

Gypsum is a soft sulfate mineral that forms extensive beds as sedimentary deposits. It is used in the production of plaster, drywall, and fertilizers. Gypsum’s ability to form crystals and its solubility in water make it a fascinating subject of study in both natural and industrial processes. Gypsum is used in drywall, plaster, cement, and as a soil conditioner.