1. Igneous Rocks Mt. Rushmore

2. Half Dome, Yosemite, CA Ansel Adams

3. Hawaii IGNEOUS ROCKS Some igneous rocks form from cooled lava that has exited Earth’s crust

4. Half Dome, Yosemite, California Some Igneous rocks cool from magma inside Earth and later become exposed through pressure, uplift, and erosion!!!

5. Igneous ignite  Think of “ignite”  To light a fire  Igneous heat Earth  Igneous rock comes from the heat within Earth: Geothermal ignite  Think of “ignite”  To light a fire  Igneous heat Earth  Igneous rock comes from the heat within Earth: Geothermal

6. How are Igneous Rocks Classified? Igneous rocks are classified by:  1. Mineral Composition  2. Crystal Size (Texture) Igneous rocks are classified by:  1. Mineral Composition  2. Crystal Size (Texture)

7. Igneous Rock Formation  Most Igneous rocks form directly from Magma which is hot, molten rock  Granite is the most common igneous rock, it cooled from magma Igneous rocks can also form from lava  Most Igneous rocks form directly from Magma which is hot, molten rock  Granite is the most common igneous rock, it cooled from magma Igneous rocks can also form from lava

8. 3. First Classification of Magma: Felsic  Is rich in Silica (SiO 2 )  Small amounts of Ca, Fe, Mg (Calcium, Iron, & Magnesium)  Slow-moving, thick= HIGH VISCOSITY (resistance to flowing) light-colored  Crystallizes to light-colored minerals low density  Resulting rocks have relatively low density continents  Felsic rocks make up the continents Felsic  Is rich in Silica (SiO 2 )  Small amounts of Ca, Fe, Mg (Calcium, Iron, & Magnesium)  Slow-moving, thick= HIGH VISCOSITY (resistance to flowing) light-colored  Crystallizes to light-colored minerals low density  Resulting rocks have relatively low density continents  Felsic rocks make up the continents

9. Rhyolite Pumice Examples of FELSIC igneous rocks

10. Mafic Silica  Low amounts of Silica (SiO 2 )  Fe and Mg rich (Iron and Magnesium)  Fast  Fast-moving, thinner = LOW Viscosity: less resistance to flowing, more fluid dark-colored  Crystallize to dark-colored minerals high density  Resulting rocks have relatively high density ocean floors  Mafic rocks make up the ocean floors Mafic Silica  Low amounts of Silica (SiO 2 )  Fe and Mg rich (Iron and Magnesium)  Fast  Fast-moving, thinner = LOW Viscosity: less resistance to flowing, more fluid dark-colored  Crystallize to dark-colored minerals high density  Resulting rocks have relatively high density ocean floors  Mafic rocks make up the ocean floors 4. Second Classification of Magma:

11. Mafic Igneous Rock examples: Basalt (ocean floor) Gabbro

12. 5. Crystal Size time  It takes time to grow crystals crystallizes  As magma cools, it crystallizes slowly  If magma cools slowly, what size crystals will form? time  It takes time to grow crystals crystallizes  As magma cools, it crystallizes slowly  If magma cools slowly, what size crystals will form? Large Crystals If Magma cools quickly, small crystals will form because they have little time to grow.

13. Igneous Rock Obsidian is dark in color due to iron oxides. Obsidian cools so fast that no crystals have time to form A.K.A. Volcanic glass Obsidian cools so fast that no crystals have time to form A.K.A. Volcanic glass

14. 6. Igneous Rocks Intrusive  Intrusive  Igneous rock that crystallizes below Earth’s surface, from magma  Intrusive= Inside Earth Intrusive  Intrusive  Igneous rock that crystallizes below Earth’s surface, from magma  Intrusive= Inside Earth Granite Large Crystal size Notice how Granite has large crystals, it cooled slowly from magma deep beneath Earth’s surface

15. Igneous Rocks Extrusive  Extrusive  Igneous rock that crystallizes or forms at Earth’s surface, from lava  Extrusive= exited Earth Extrusive  Extrusive  Igneous rock that crystallizes or forms at Earth’s surface, from lava  Extrusive= exited Earth Basalt Small Crystal size Notice how basalt has small crystals, it cooled quickly at Earth’s surface

16. Lava is magma Lava is magma that has reached the Earth’s surface.

17. Igneous Rocks  EXT-rusive  EXITED Earth  IN-trusive  Formed IN-side Earth  EXT-rusive  EXITED Earth  IN-trusive  Formed IN-side Earth

18. Crystal Size  Intrusive Rock (Large Crystal Size)  Because it is inside the Earth, it cools very slowly, giving crystals time to grow  Extrusive Rock (Small crystal size)  Cools very quickly so crystals do not have time to form  Intrusive Rock (Large Crystal Size)  Because it is inside the Earth, it cools very slowly, giving crystals time to grow  Extrusive Rock (Small crystal size)  Cools very quickly so crystals do not have time to form

19. Composition (what it’s made of) of Granite Granite Rock contains the following minerals:  Quartz  Feldspar  Mica Granite Rock contains the following minerals:  Quartz  Feldspar  Mica

20. Igneous Rock Felsic (Light Color) Continents Mafic (Dark Color) Ocean Floor Intrusive Cools slowly From Magma Large crystals (SiO 2 ) rich Large crystals Fe, Mg rich Extrusive Cools quickly From Lava Small or no crystals (SiO 2 ) rich Small or no crystals Fe, Mg rich

21. Igneous Rock Felsic (Light Color) Continents Mafic (Dark Color) Ocean Floor Intrusive Cools slowly From Magma Large crystals (SiO 2 ) rich Large crystals Fe, Mg rich Extrusive Cools quickly From Lava Small or no crystals (SiO 2 ) rich Small or no crystals Fe, Mg rich

22. Igneous Rock Felsic (Light Color) Continents Mafic (Dark Color) Ocean Floor Intrusive Cools slowly From Magma Large crystals (SiO 2 ) rich Large crystals Fe, Mg rich Extrusive Cools quickly From Lava Small or no crystals (SiO 2 ) rich Small or no crystals Fe, Mg rich

23. Igneous Rock Felsic (Light Color) Continents Mafic (Dark Color) Ocean Floor Intrusive Cools slowly From Magma Large crystals (SiO 2 ) rich Large crystals Fe, Mg rich Extrusive Cools quickly From Lava Small or no crystals (SiO 2 ) rich Small or no crystals Fe, Mg rich

24. Igneous Rock Felsic (Light Color) Continents Mafic (Dark Color) Ocean Floor Intrusive Cools slowly From Magma Large crystals (SiO 2 ) rich Large crystals Fe, Mg rich Extrusive Cools quickly From Lava Small or no crystals (SiO 2 ) rich Small or no crystals Fe, Mg rich

25. Igneous Rock Felsic (Light Color) Continents Mafic (Dark Color) Ocean Floor Intrusive Cools slowly From Magma Large crystals (SiO 2 ) rich Large crystals Fe, Mg rich Extrusive Cools quickly From Lava Small or no crystals (SiO 2 ) rich Small or no crystals Fe, Mg rich

26. IGNEOUS  FELSIC  Light colored  Less dense  Rich in silica (SiO 2 )  Magma flows slowly, thick  Continental crust  FELSIC  Light colored  Less dense  Rich in silica (SiO 2 )  Magma flows slowly, thick  Continental crust

27. IGNEOUS  MAFIC  Dark colored  Very dense  Rich in iron (Fe) and magnesium (Mg)  Magma flows quickly, thin  Oceanic crust  MAFIC  Dark colored  Very dense  Rich in iron (Fe) and magnesium (Mg)  Magma flows quickly, thin  Oceanic crust

28. IGNEOUS  EXTRUSIVE  “exit”  Magma exits the Earth before cooling  Cools and crystalizes quickly  Small or no crystals  EXTRUSIVE  “exit”  Magma exits the Earth before cooling  Cools and crystalizes quickly  Small or no crystals

29.  INTRUSIVE  “in”  Magma cools inside the Earth  Cools and crystalizes slowly  Large crystals  INTRUSIVE  “in”  Magma cools inside the Earth  Cools and crystalizes slowly  Large crystals IGNEOUS

30. Igneous Rock Lab  Use your Igneous observations sheet  Rotate independently between the 25 stations set up around the room  Start with whichever station number you are located  Round 1: You will have less than 1 minute at each station  Do not switch to the next station until told to do so, only 1 person at at station (if you have extra time, study your notes)  Round 2: You may go back to any unoccupied station, if needed  Use your Igneous observations sheet  Rotate independently between the 25 stations set up around the room  Start with whichever station number you are located  Round 1: You will have less than 1 minute at each station  Do not switch to the next station until told to do so, only 1 person at at station (if you have extra time, study your notes)  Round 2: You may go back to any unoccupied station, if needed