1. http://www.ehow.co.uk/video_4774969_identifying-igneous-rocks.html http://www.videojug.com/film/geology-igneous-rocks

2. Vocabulary  Magma Molten rock beneath Earth’s surface  Lava Molten rock that reaches Earth’s surface through a volcano

3. Igneous Rocks… Igneous Rocks are classified on what minerals make up the rock and the size of mineral crystals. Formation Mineral Composition Origin Crystal Size Color Cooling Time

4. Origin of Igneous Rocks  Intrusive Forms when magma cools within Earth Magma cools slowly being exposed to high temperatures Reach surface when forces inside Earth push rocks up & wind and water break apart/carry away surface rocks  Extrusive Forms when lava cools on Earth’s surface Lava cools quickly being exposed to cool temperatures Reach surface through volcanoes erupting Igneous rocks are classified as INTRUSIVE or EXTRUSIVE

5. Intrusive Igneous Rocks Granite PeridotitePegmatite Gabbro Anorthosite Diorite Forms from magma within Earth’s surface

6. Extrusive Igneous Rocks Basalt RhyoliteScoria Obsidian Andesite Pumice Forms from lava on Earth’s surface

7. Textures of Igneous Rocks Texture of an igneous rock is determined by the size of its mineral crystals. Size of mineral crystals depends on how quickly the magma or lava cools.

8. Textures of Igneous Rocks  Intrusive Interior of Earth is HOT High Temperatures allow magma to cool SLOWLY Slow cooling allows time for LARGE mineral crystals to form  Extrusive Surface of Earth is COOL Lower temperatures cause the lava to cool QUICKLY No time for large mineral crystals to form so there are SMALL mineral crystals

9. Composition of Igneous Rocks  Silica: Compound made up of silicon and oxygen which geologists use to classify rocks Texture is not enough to identify an Igneous Rock. Some Igneous Rocks have similar textures. Composition is based on Silicate levels. Estimate SILICATE level by COLOR  LIGHT COLOR HIGH LEVELS OF SILICA DARK COLOR  LOW LEVELS OF SILICADARK COLOR Granite/Rhyolite Gabbro/Basalt

10. Rocks in the World Around Us