1. Igneous Rocks Chap. 5 What are igneous rocks? Identifying igneous rocks

2. What are igneous rocks? – 5.1Objectives compare and contrast intrusive and extrusive rocks describe the composition of magma discuss the factors that affect how rocks melt and crystallize Rhyolite breccia

3. I.Definition

4. Igneous Rocks Rocks formed when magma crystallizes. ‘Ignis’ = fire

5. II.Types of Igneous rocks

6. A.Extrusive – fine grained rocks that cool quickly, on Earth’s surface II.Types of Igneous rocks Basalt

7. B.Intrusive – -grained rocks that cool, the Earth II.Types of Igneous rocks

8. B.Intrusive – coarse-grained rocks that cool slowly, under the Earth II.Types of Igneous rocks Granite

9. III. Magma composition

10. A.Molten rock III. Magma composition

11. A.Molten rock B.Gases III. Magma composition

12. A.Molten rock B.Gases C.Mineral crystals III. Magma composition

13. A.Molten rock B.Gases C.Mineral crystals D.Magma Classifications III. Magma composition

14. A.Molten rock B.Gases C.Mineral crystals D.Magma Classifications III. Magma composition 1. Basaltic – 50% SiO 2

15. A.Molten rock B.Gases C.Mineral crystals D.Magma Classifications III. Magma composition 1. Basaltic – 50% SiO 2 2. Andesitic – 60% SiO 2

16. A.Molten rock B.Gases C.Mineral crystals D.Magma Classifications III. Magma composition 1. Basaltic – 50% SiO 2 2. Andesitic – 60% SiO 2 3. Rhyolitic – 70% SiO 2

17. IV. Magma Formation is Influenced by

18. A.Temperature (increases with depth) IV. Magma Formation is Influenced by

19. A.Temperature (increases with depth) B.Pressure (as pressure ↑, melting pt. ↑) IV. Magma Formation is Influenced by

20. A.Temperature (increases with depth) B.Pressure (as pressure ↑, melting pt. ↑) C.H 2 O content (more H 2 O, melting pt. ↓) IV. Magma Formation is Influenced by

21. A.Temperature (increases with depth) B.Pressure (as pressure ↑, melting pt. ↑) C.H 2 O content (more H 2 O, melting pt. ↓) D.Mineral content IV. Magma Formation is Influenced by Granite has higher water content so it melts at a temperature

22. A.Temperature (increases with depth) B.Pressure (as pressure ↑, melting pt. ↑) C.H 2 O content (more H 2 O, melting pt. ↓) D.Mineral content IV. Magma Formation is Influenced by Granite has higher water content so it melts at a lower temperature

23. V. Melting Rocks

24. A.Partial melting V. Melting Rocks Some minerals melt while others remain solid

25. A.Partial melting V. Melting Rocks Some minerals melt while others remain solid HEAT

26. A.Partial melting B.Fractional crystallization V. Melting Rocks As liquid rock cools certain minerals crystallize before others

27. A.Partial melting B.Fractional crystallization V. Melting Rocks As liquid rock cools certain minerals crystallize before others COOLING

28. A chart that shows how minerals crystallize when cooled VI. Bowen’s Series

29. A.Two paths VI. Bowen’s Series

30. A.Two paths VI. Bowen’s Series 1.Continuous path for feldspars

31. A.Two paths VI. Bowen’s Series 1.Continuous path for feldspars 2. Stepwise path for Fe/Mg minerals

32. A.Two paths B.Both paths end with Si and O – the last minerals to crystallize VI. Bowen’s Series

33. VI. Intrusions

34. A.Quartz (SiO 2 ) finds way into rock veins VI. Intrusions Quartz vein

35. A.Quartz (SiO 2 ) finds way into rock veins B.Intruded masses of rock cool in layers, often carrying metals (gold, silver, and platinum) VI. Intrusions

36. The End

37. Classifying Igneous Rocks 5.2 Objectives Classify different types and textures of igneous rocks Recognize the effects of cooling rates on the grain sizes Describe some uses of igneous rocks Basalt

38. I.Where rock forms

39. A.Intrusive forms.

40. I.Where rock forms A.Intrusive forms under surface. B.Extrusive forms.

41. I.Where rock forms A.Intrusive forms under surface. B.Extrusive forms above surface.

42. II. Rock’s composition

43. A.Felsic – silicon-rich, light colored Granite

44. II. Rock’s composition A.Felsic – silicon-rich, light colored B.Mafic – iron & magnesium rich, dark colored Gabbro

45. II. Rock’s composition A.Felsic – silicon-rich, light colored B.Mafic – iron & magnesium rich, dark colored C.Ultramafic – very high levels of Fe & Mg Peridotite

46. III. Texture A.Phaneritic has coarse grains Granite

47. III. Texture B.Aphanitic is fine-grained Basalt

48. III. Texture C.Vessicular – has tiny holes Vessicular Basalt

49. III. Texture D.Glassy – has no visible grains Obsidian

50. III. Texture E.Porphyritic – has large grains surrounded by smaller grains Andesite

51. IV. Igneous rocks as resources

52. A.They are strong and resist weathering

53. B.Granite is a common construction material IV. Igneous rocks as resources

54. V. Ores Minerals that contain useful substances that are mined for profit

55. A.Important metallic elements often found near veins V. Ores

56. A.Important metallic elements often found near veins B.Pegmatites V. Ores Veins of extremely large-grained minerals

57. A.Important metallic elements often found near veins B.Pegmatites C.Kimberlites V. Ores These contain diamonds

58. The End