1. Igneous Rocks Created By: Mr. Kreeger

2. Homework and Page References Page References- 63-68 Page References- 63-68 HW #1- 1-8 on page 68 HW #1- 1-8 on page 68 HW #2- Choose 5 Igneous rocks on the chart and list the following information. HW #2- Choose 5 Igneous rocks on the chart and list the following information. –Color index –Dominant minerals –Texture –How and where it formed

3. Table of Contents 1. Formation of Igneous Rocks 2. Characteristics of Igneous Rocks a.Texture b.Mineral Composition 3. Textures of Igneous Rocks a.Intrusive 1. Pegmatic (Very coarse grained) 2. Phaneritic (Coarse grained) b.Extrusive 1. Aphanitic (Fine Grained) 2. Glassy 3. Vesicular (Gas Bubbles) 4. Pyroclastic (particles from volcano) c.Intrusive and Extrusive 1. Porphyritic 4. Mineral Composition a.Felsic b.Mafic 5. How to Identify Igneous Rocks

4. Introduction Video

5. Igneous Rock ID Chart Page 6 of ESRT

6. 1. Formation of Igneous Rocks Form as the result of cooling or solidification of Magma. Form as the result of cooling or solidification of Magma. LIQUID HOT MAGMA LIQUID HOT MAGMA –Mixture of hot liquid rock, gases and crystals –Less dense than surrounding rock so it moves upward Magma that reaches surface (lava) erupts and solidifies- Extrusive IR Magma that reaches surface (lava) erupts and solidifies- Extrusive IR Magma that cools underground-Intrusive IR Magma that cools underground-Intrusive IR

7. 2. Characteristics of Igneous Rocks a. Texture- The size, shape and arrangement of the mineral crystals or grains of rocks. Slow cooling- Large Crystals, intrusively formed Slow cooling- Large Crystals, intrusively formed Rapid cooling- Small Crystals, extrusively formed Rapid cooling- Small Crystals, extrusively formed b. Mineral Composition- Minerals that make up the rock. Made of a combination of 8. (Muscovite and biotite mica, Quartz, Potassium and Plagioclase Feldspar, Amphibole, Pyroxene and Olivine)

8. Pictures of 8 minerals that comprise Igneous Rocks Felsic Mafic

9. 3. Textures of Igneous Rocks a. Intrusive (Plutonic) Magma trapped underground and solidifies. As a result of slow cooling large crystals are able to form.

10. 3a. Intrusive Igneous Rocks 1. Pegmatic (Very Coarse)- Crystals >10mm, very slow cooling. (Pegmatite) 2. Phaneritic (Coarse) Crystals 1-10mm, slow cooling. Granite and (Gabbro)

11. 3. Textures of Igneous Rocks b. Extrusive (Volcanic) Formed from the rapid cooling of lava result the rock has a very fine structure and sometimes none at all

12. 3b. Extrusive Igneous Rocks 1. Aphanitic (fine texture) crystals <1mm.(Rhyolite) 2. Glassy- Result of rapid cooling no visible crystals at all. (Obsidian) 3. Vesicular- Rapid cooling of gas filled lava, has holes. (Pumice) 4. Pyroclastic- Particles emitted from volcanoes.

13. 3c. Intrusive and Extrusive 1. Porphyritic- Has both small and large crystals. Result of cooling underground- Large Crystals (Phenocrysts) and rapid cooling above ground (Groundmass or matrix)

14. 4. Mineral Composition a. Felsic Group- Igneous rock contains mostly Quartz, Potassium and Plagioclase Feldspar, tend to be light colored and low density. b. Mafic Group- Igneous rock contains mostly Olivine, pyroxene, and amphibole, tend to be dark colored and higher in density.

15. 5. How to Identify Igneous Rocks 1. Identify rocks color index Light Colored- Felsic Light Colored- Felsic Dark Colored- Mafic Dark Colored- Mafic 2. Identify mineral composition by Color index. 3. Identify Rocks Texture Intrusive- large crystals Intrusive- large crystals Extrusive- Small or no crystals or gas bubbles. Extrusive- Small or no crystals or gas bubbles.