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Igneous Rocks Igneous Rocks are made from minerals melted deep inside the Earth When these melted minerals cool they form different kinds of Igneous rocks. -When melted minerals are under the earth’s crust they are called Magma. -When melted minerals are above the earth’s crust they are called Lava. Pumice is an Igneous rock that is formed when air bubbles are trapped in cooling lava above the Earth’s crust. Pumice is often called “Lava Rock.” Obsidian is another type of Igneous rock that is formed when lava, with no air bubbles, cools QUICKLY above the Earth’s crust. Obsidian is so hard and shiny, it is often called volcanic glass. Native Americans used this type of Igneous rock to form arrow and spear heads. Other types of Igneous rocks are formed when melted minerals cool and harden slowly under the Earth’s crust. Basalt is an Igneous rock that is formed when magma cools slowly above the earth’s crust. -Granite is another Igneous rock that is formed when magma cools slowly under the earth’s crust. -Granite is often used in the construction of buildings, like for counter tops. The different types of Igneous rocks we have learned about today are: Pumice Obsidian Basalt Granite So remember! Igneous rocks are formed from molten (melted) minerals that cool either above or under the earth’s surface.