**Granite Composition and Petrology**:
– Granite is a coarse-grained igneous rock composed of quartz, alkali feldspar, and plagioclase.
– Granitic rocks are classified based on the percentages of quartz, alkali feldspar, and plagioclase.
– Granites can be white, pink, or gray in color depending on mineralogy.
– Granites are rich in silica, alumina, and alkali metal oxides.
– Granitic rocks contain varying amounts of muscovite, biotite, and amphibole.
**Granite Formation and Geological Significance**:
– Granite forms from silica-rich magmas known as felsic magmas.
– Granitic rock is widely distributed throughout the continental crust.
– Granites often occur in circular depressions surrounded by hills.
– Granitic rocks are common in continental arc settings, with batholiths extending along the arc.
– Differentiation between granite types aids in understanding geological processes.
**Granite Magmatic Processes**:
– Magma ascends through the crust via diapiric ascent.
– Fractional crystallization reduces magnesium and enriches the melt in iron and potassium.
– Granitic melts are produced through partial melting of metamorphic rocks.
– Granitic rocks in island arcs show fractional crystallization can convert basaltic magma to granitic magma.
– Magma rises in small channels along self-propagating dykes.
**Granite Environmental Impact**:
– Granite weathering contributes to soil formation.
– Chemical weathering occurs through hydrolysis altering feldspar.
– Radon gas can accumulate in cellars built over granite.
– Climatic variations influence the weathering rate of granites.
– Soil development on granite reflects its high quartz content and acidification.
**Granite Uses and Cultural Significance**:
– Ancient Egyptians used granite in pyramids, columns, and temples.
– Granite is extensively used as dimension stone and flooring tiles.
– Granite industry is considered one of the oldest industries in the world.
– Granite has been a significant material in historic construction and art.
– Granite has been used in ancient Egyptian and Korean architecture, showcasing its cultural and historical significance.
