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Minerals And Their Mode Of Occurrence Video Lecture | Geography for Class 8

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FAQs on Minerals And Their Mode Of Occurrence Video Lecture - Geography for Class 8

1. What are minerals and how do they occur?
Ans. Minerals are naturally occurring inorganic substances that have a definite chemical composition and crystal structure. They occur in different ways such as: - Crystallization from magma: When molten rock cools and solidifies, minerals crystallize from the magma, forming igneous rocks. - Precipitation from solution: Some minerals can be formed when elements or compounds dissolve in water and then precipitate out, forming sedimentary rocks. - Metamorphic changes: Existing minerals can undergo changes in pressure, temperature, or chemical environment to form new minerals, known as metamorphic rocks.
2. What is the mode of occurrence of minerals in sedimentary rocks?
Ans. Minerals in sedimentary rocks occur through the process of precipitation from solution. When water containing dissolved minerals evaporates or becomes oversaturated, the minerals precipitate out and accumulate over time. Examples of minerals found in sedimentary rocks include halite (rock salt), gypsum, and limestone.
3. How do minerals occur in igneous rocks?
Ans. Minerals in igneous rocks occur through the process of crystallization from magma. When molten rock cools and solidifies, minerals start to form as the elements combine and arrange themselves in a specific pattern. The cooling rate, pressure, and composition of the magma determine the types of minerals that will crystallize. Examples of minerals found in igneous rocks include quartz, feldspar, and mica.
4. What is the role of metamorphic changes in the occurrence of minerals?
Ans. Metamorphic changes play a significant role in the occurrence of minerals. When existing minerals are subjected to high temperatures, pressure, or chemical alteration, they can undergo physical and chemical changes, leading to the formation of new minerals. The minerals formed during metamorphism depend on the composition of the original minerals and the conditions under which the changes occur. Examples of minerals that can form through metamorphic changes include garnet, marble, and schist.
5. Can minerals occur in more than one mode of occurrence?
Ans. Yes, minerals can occur in more than one mode of occurrence. For example, quartz can be found in igneous rocks as a primary mineral formed through crystallization from magma, but it can also occur in sedimentary rocks when it is transported and deposited by water. Similarly, limestone can form through the precipitation of calcium carbonate from solution in sedimentary rocks, but it can also undergo metamorphism to form marble. The occurrence of minerals in different modes depends on the geological processes and conditions they are exposed to.
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