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Question
How are igneous rocks classified on the basis of their chemical composition?
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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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