Igneous Rocks

Caption: granite, an igneous rock

All rocks can be put into one of three groups. The groups are based on how the rock was formed. Some rocks are formed slowly near the surface of the Earth. Other rocks are formed deep underground by extreme heat and pressure. One kind of rock is formed when particles of rock, minerals, or crystals get so hot that they melt. The rock that is formed when this melted rock cools is called igneous rock. The Earth's core is very hot. .....

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