Rock-forming minerals are minerals that are commonly found in the Earths crust and are responsible for the formation of various types of rocks. These minerals make up the majority of the Earths crust. There are thousands of naturally occurring minerals on Earth in rocks, but most are very rare. Most rocks are composed of very common rock-forming minerals. Knowing about these common minerals makes understanding most rocks easy. The common rock-forming minerals are:
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Feldspars: Feldspars are the most common mineral group in the Earths crust. They are aluminum silicates that contain potassium, sodium, or calcium.
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Quartz: Quartz is a mineral composed of silicon and oxygen atoms. It is the second most abundant mineral in the Earths crust.
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Amphiboles: Amphiboles are a group of minerals that are typically dark-colored and contain iron, magnesium, and calcium. They are common in igneous and metamorphic rocks.
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Micas: Micas are a group of minerals that are typically shiny and flaky. They are common in igneous and metamorphic rocks and are often used in electrical insulation.
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Olivine: Olivine is a green mineral that is common in igneous rocks. It is composed of magnesium, iron, and silicon.
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Garnet: Garnet is a group of minerals that are typically red or brown and contain aluminum, iron, and calcium. They are common in metamorphic rocks.
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Calcite: Calcite is a mineral composed of calcium, carbon, and oxygen. It is common in sedimentary rocks and is often used in the production of cement and lime.
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Pyroxenes: Pyroxenes are a group of minerals that are typically dark-colored and contain iron, magnesium, and calcium. They are common in igneous and metamorphic rocks.
Clay minerals, such as kaolinite, montmorillonite, and illite, are also common in sedimentary rocks, particularly shales.
