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| Igneous rocks are formed by heat and very high pressure. Igneous means made by heat. They were the first rocks on the earth and they are also known as primary rocks. When molten lava comes out of a volcano, it is very hot. When the magma cools and hardens, it turns into igneous rock. That is how igneous rock is formed. Here is a list of all the different kinds of igneous rocks there are. | |
| Andesite | |
| Basalt |
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| Dike | |
| Diorite |  Photos courtesy of Pamela J. W. Gore, Georgia Perimeter College |
| Dolerite | |
| Felsite | |
| Gabbro |  Photos courtesy of Pamela J. W. Gore, Georgia Perimeter College |
| Granite |
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| Jointing | |
| Microdiorite | |
| Microgranite | |
| Obsidian |
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| Pegmatite | |
| Peridotite |  Photos courtesy of Pamela J. W. Gore, Georgia Perimeter College |
| Pitchstone | |
| Pumice |
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| Rhyolite |  Photos courtesy of Pamela J. W. Gore, Georgia Perimeter College |
| Serpentinite | a |
| Syenite |  Photos courtesy of Pamela J. W. Gore, Georgia Perimeter College |
| Trachyte | |
| Ultrabasic rock | |
| Xenolith | |