My+Rocks

Rock Families Igneous rock forms from melted rock (lava or magma) when it cools When lava and magma cool, they form two different kinds of Igneous rock: 1. **__Intrusive rock__** – igneous rock that is formed from cooled magma (e.g. granite) 2. **__Extrusive rock__** – igneous rock that is formed from cooled lava (e.g. pumice)
 * There are three rock families:
 * #1 Igneous
 * #2 Sedimentary
 * #3 Metamorphic
 * **#1 Igneous Rock** – “Born of Fire”
 * __Lava__** – melted rock that is found outside (“on”) the Earth’s crust
 * __Magma__** – melted rock that is found inside the Earth’s crust
 * The main difference between intrusive and extrusive rock is their crystal size, which depends on how quickly they cool.
 * **__Extrusive rock__** (from lava) cools quickly and forms small crystals.
 * **__Intrusive rock__** (from magma) cools very slowly inside the Earth’s crust and forms large crystals.

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