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Question
How are igneous rocks classified on the basis of their chemical composition?
Solution
On the basis of chemical composition igneous rocks may be classified into two groups i.e. Acid igneous rocks and Basic igneous rocks. Acid rocks have silica content 65-85 percent e.g. granite which is made up of large crystals of quartz, feldspar and mica. Basic rocks contain high percentage oxides of denser material, silica content is between 40-60 percent with a density of 2.8 g/cm3 and 3.0 g/cm3. Acid rocks are lighter than Basic rocks.
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