Composition of Crust: Minerals, Rocks and Elements

Minerals are natural substances with specific chemical structures. Most of Earth’s crust is crafted from eight main minerals, including oxygen, silicon, and others. From sparkling quartz to sturdy feldspar, these minerals come together to create the diverse rocks we see all around us. Let’s take a closer look at these fascinating components that shape our planet’s surface.

Minerals in the Earth’s Crust

• Majority of Eight Elements: About 98 per cent of the total crust of the earth is composed of eight elements – oxygen, silicon, aluminium, iron, calcium, sodium, potassium and magnesium.
• Minerals: These are naturally occurring substances that have an orderly atomic structure and a definite chemical composition & physical properties. 
  • A mineral is composed of two or more elements. But, sometimes single-element minerals like sulphur, copper, silver, gold, graphite etc. are found.  
  • The basic source of all minerals is hot magma in the interior of the earth.
• When magma cools, it forms crystals of minerals, which then arrange themselves in a specific order to create rocks.
• Minerals that contain metals are known as metallic minerals, such as Haematite, and those that are economically viable to mine are called ores.
• The table below shows the percentage-wise share of each element of Earth’s Crust and the Entire Earth.

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• Earth’s crust contains over 2,000 minerals, but only six of them are very common and make up most of it.
• The six most abundant minerals are feldspar, quartz, pyroxenes, amphiboles, mica, and olivine.
  • Feldspar and quartz are the most common minerals found in rocks
  • Feldspar: Half of the earth’s crust is composed of feldspar; Silicon and Oxygen are common elements of all types of feldspar; used in ceramic and glass making.
  • Quartz: is one of the most important components of sand and granite; it consists of silica. 
  • Pyroxene: consists of calcium, aluminium, magnesium, iron and silica; commonly found in meteorites.
  • Amphibole: Major elements- aluminium, calcium, silica, iron, and magnesium; used in the asbestos industry.
  • Mica: comprises potassium, aluminium, magnesium, iron, silica etc; commonly found in igneous and metamorphic rocks; used in electrical instruments.
  • Olivine: Major elements- magnesium, iron, and silica; used in the jewellery industry; often found in basaltic rocks.
• Metallic minerals: contain metal content
  • Precious Metals: gold, silver, platinum, etc.
  • Ferrous Metals: iron and other metals often mixed with iron to form various kinds of steel.
  • Non-ferrous Metals: include metals like copper, lead, zinc, tin, aluminium etc
• Non-metallic minerals: do not contain metal content.
  • Example: Sulphur, phosphates and nitrates. Cement is a mixture of non-metallic minerals.

Conclusion

• Earth’s crust is predominantly made up of eight key elements, with oxygen and silicon being the most abundant. 
• These elements combine to form a diverse array of minerals, with six main ones dominating the crust. These minerals, including feldspar, quartz, and mica, play crucial roles in shaping the rocks and landscapes we see on the Earth’s surface. 
• Metallic and non-metallic minerals contribute to various industries, from construction to electronics, highlighting the importance of understanding Earth’s mineral composition.

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