Igneous Rock Essay

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I. Igneous Rock This major type of rock is formed when molten rock material, usually from Earth’s hot spots, rises towards the surface then crystallizes and solidifies. Igneous rocks have two types, varying on where the molten rock material solidifies.

The following are examples of igneous rocks which are used as a building material:

1) Granite

Granite is classified as intrusive igneous rock and plutonic. Granite is formed when a magma rich in Silica is cools down in a deeply buried body (or pluton) and forms then hardens into a rock without reaching the surface.

Due to the slow cooling process, granite has large mineral grain that fit together. Granite always consist of the minerals quartz and feldspar which gives granite a light color. They say, “It is not granite without quartz.”
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Dolerite is formed when it cools under basaltic volcanoes, such as mid ocean ridges. It cools moderately quickly as the magma moves up into the cracks and weak zones of a volcano. Due to the moderate cooling, its crystals appear to be small and visible.

Diabase have ample deposits in shallow intrusive bodies such as dikes (tabular bodies inserted in fissures), sills (tabular bodies inserted while molten between other rocks), and the like.

This dark colored rock is mainly compromised by the essential minerals plagioclase feldspar of labradorite composition and pyroxene of augite composition. At the same time, other accessory minerals can also be found in diabase such as magnetite, olivine or quarts which results variations to diabase rocks. Diabase are the medium-grained equivalents of

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