[Geography Notes] on Mineral Chemical Compound – Occurrence and Formation Pdf for Exam

Minerals are naturally occurring inorganic solids found in the earth’s crust and they are either made up of one element or they are a combination of elements. Most minerals are highly valuable and their study, classification, and excavation all fall under the subject of geology. In this article, we will discuss the occurrence and formation of minerals. Several factors affect the formation of a mineral. Since minerals occur in a wide variety of environments, we have a wide array of these resources forming under various chemical and physical conditions. If we classify minerals based on their process of forming, we will have four types, namely: igneous, sedimentary, metamorphic, and hydrothermal. 

Minerals Found in Igneous Rocks

Igneous rocks form due to the cooling and solidification of lava. The minerals occurring in these rocks are igneous. Partial melts of previously formed rocks exist in the earth’s crust and mantle and at times due to tectonic tensions, the molten mass travels towards the surface and starts cooling. If they solidify below the earth’s surface, they form intrusive rocks and otherwise they form extrusive rocks. The mineral compounds which exist in the earth’s mantle travel to the surface with the lava and then solidify as part of an igneous rock. This process leads to the formation of igneous minerals. Some igneous minerals are olivines, pyroxenes, and micas. 

Minerals Found in Sedimentary Rocks

Minerals found in sedimentary rocks are a result of the process of sedimentation. In this process, rocks and soil undergo erosion by the various forces of nature, including wind and water. These eroded particles travel to different regions and settle layer by layer in certain places. In these regions, structures formed of sedimentary rocks come to life. Sedimentary rocks contain many valuable minerals such as quartz, feldspar, calcite, dolomite, etc. 

Minerals Found in Metamorphic Rocks 

Metamorphic rocks form due to the complete metamorphosis of existing rocks. Metamorphosis means transformation and this change occurs due to certain physical phenomena. Environmental changes such as an increase or decrease in temperature or pressure lead to chemical changes in the mineral compounds of rocks to give rise to new minerals. This process is the basis of the occurrence of metamorphic minerals. Some examples of such minerals are garnet, corundum, and kyanite. 

Minerals Found in Hydrothermal Rocks 

Hydrothermal minerals occur in the fissures of rocks and form as a result of the chemical precipitation of hot solutions erupting from the earth’s core. In the previous three types, we observe that minerals are closely intergrown within the rocks in an interlocking pattern. However, hydrothermal solutions tend to flow into the fractures in a rock structure to gain a suitable space for chemical precipitation of the minerals in the solution. Geologists collect their samples from these very fissures. When a mineral undergoing precipitation grows without any external disturbance, beautifully shaped crystals come to life. This crystalline form gives an aesthetic appeal to the minerals. 

Petroleum: Formation and Occurrence 

This section is a short discussion on petroleum formation and occurrence. Petroleum is a very crucial industrial mineral. Petroleum is a result of the slow decomposition of organic matter due to chemical biochemical factors. This mineral naturally occurs in layers between sedimentary rocks. The trapped organic matter undergoes decomposition by bacterial action and changes in the chemical environment. This process turns the organic waste into globules of oil and gas. 

Questions and Answers

Q1. Explain the term Minerals and State their Importance. 

Answer: Minerals are solid inorganic compounds naturally occurring in rocks in the earth’s crust. Minerals are highly valuable commercially and industrially. Coal, natural gas, and petroleum act as fuels. Several other minerals find application in medicines, fertilizers, etc. 

Q2. Name the Softest and Hardest Minerals. 

Answer: Talc is the softest naturally occurring mineral and diamond is the hardest one. 

Q3. Explain the reason behind the Wide Variety in the Colour, Texture, Lustre and Hardness of Minerals. 

Answer: The physical properties of minerals are widely spread when it comes to colour, density, hardness, lustre, etc. This variety yields from the fact that each mineral is formed from a particular set of elements under particular environmental conditions, making them unique.