1. © 2006 Pearson Prentice Hall This work is protected by United States copyright laws and is provided solely for the use of instructors in teaching their courses and assessing student learning. Dissemination or sale of any part of this work (including on the World Wide Web) will destroy the integrity of the work and is not permitted. The work and materials from it should never be made available to students except by instructors using the accompanying text in their classes. All recipients of this work are expected to abide by these restrictions and to honor the intended pedagogical purposes and the needs of other instructors who rely on these materials. Lecture Outlines PowerPoint Chapter 2 Earth Science 11e Tarbuck/Lutgens

2. Earth Science, 11e Minerals: Building Blocks of Rocks Chapter 2

3. Minerals are essential: They ’ re every manufactured product They ’ re essential to good health Knowledge of minerals enables us to understand earth processes

4. Minerals: the building blocks of rocks  Definition of a mineral: What are the 5 characteristics that make a mineral? Natural (found in nature) Have a definite chemical composition (chemical formula) Possess an orderly internal structure of atoms (A.K.A. crystal structure) Solid Inorganic (never living) Mineraloid - lacks an orderly internal structure

5. Composition and structure of minerals  Elements Basic building blocks of minerals Over 100 are known What is the #1 most abundant element in the Earth ’ s crust????? Atoms Smallest particles of matter Have all the characteristics of an element

6. Composition of continental crust Figure 2.16

7. Periodic table of the Elements Figure 2.4

8. Simplified view of the atom Figure 2.5

9. How atoms are constructed  __________ central part of an atom that contains ___________ positive electrical charges ___________ neutral electrical charges  Energy levels, or shells Surround nucleus Contain __________ negative electrical charges Nucleus Protons Neutrons electrons

10. How atoms are constructed  _______ _________ is the number of protons in an atom's nucleus  Bonding of atoms Forms a compound with two or more elements Ionic bonds and metalic bonds _______are atoms that gain or lose electrons  ___________ Have varying number of neutrons and are radioactive Atomic number Ions Isotopes

11. How atoms are constructed  Isotopes Have different mass numbers – the sum of the neutrons plus protons Many isotopes are radioactive and emit energy and particles

12. How minerals form: 1.Underground in the magma process (most minerals) 2. Re-form deep within the earth in the pressure process. 3. Near the surface in the evaporation (of water) process

13. How Minerals form The Magma Process: 1.Molten (liquid) rock in a magma chamber At, near or under earth ’ s surface, rises 2. The magma begins to cool and atoms, ions and molecules form various mineral compounds. 3. The molecules of the compounds mass together to form crystals.

14. The Pressure Process: 1. Rock is exposed to high pressures and temperatures, and the minerals begin to break down. 2. As pressure and temperature continue, the molecules RE-FORM into new minerals. 3. The minerals are elongated in shape due to the pressure.

15. The Evaporation Process: 1. Ions (such as salt or calcium) are dissolved in water. 2. The water evaporates, and the ions form minerals such as halite and calcite. Examples: halite (NaCl salt) » limestone (calcite)

16. Minerals  Physical properties of minerals Crystal form Luster Color Streak Hardness Cleavage

17. The mineral quartz often exhibits good crystal form

18. Factors that determine crystal formation: 1.Time 2.Space 3.Evaporation Rate 4.Dissolved Materials 5.Temperature 6.Pressure Largest uncut diamond found in the Letseng Mine in southern Africa. A near-flawless white gem weighing nearly 500 carats. It was discovered on Sept. 8, 2008 It weighs 478 carats, with very few inclusions and of outstanding color and clarity.

22. MexicoMexico's Cueva de los Cristales (Cave of Crystals) contains some of the world's largest known natural crystals—translucent beams of gypsum as long as 36 feet (11 meters). Volcanic activity that began about 26 million years ago created Naica mountain and filled it with high-temperature anhydrite gypsum. When magma underneath the mountain cooled and the temperature dropped, the anhydrite began to dissolve and for millions of years have been deposited in the caves in the form of huge selenite gypsum crystals.

23. 1. TIME and mineral formation The RATE at which the molten magma cools determines the crystal size.

24. If the magma has a lot of time and it cools s-l-o-w-l-y then the crystals will…. * (example: granite) LARGE and well-formed

25. If the magma cools quickly, then the crystals will…. *example: obsidian has a glass-like structure Small / microscopic / not well-formed

26. Classzone Internet Investigation ES0506 “ How Do Crystals Grow? ” 2. Space 3. Evaporation rate 3. Amount of dissolved materials 3. Temperature 4. Pressure http://www.classzone.com/books/earth_science/terc/content/investigations/es0506/

27. Summarize in a sentence: So…. To grow the biggest, best synthetic diamond crystal, you would…. time, space, cooling rate (temperature) pressure

28. Pyrite (fool ’ s gold) displays metallic luster Figure 2.10

29. Figure 2.12 Mohs scale of hardness

30. Minerals  Physical properties of minerals Fracture Specific gravity Other properties Taste Smell Elasticity Malleability

31. Minerals  Physical properties of minerals Other properties Feel Magnetism Double Refraction Reaction to hydrochloric acid Fluorescence (UV)

32. Some rocks and minerals “ glow ” under UV (black) light

33. Minerals  A few dozen minerals are called the rock-forming minerals The eight elements that compose most rock-forming minerals are… OXYGEN (O) (46.6% by weight) SILICON (Si), (27.7% by weight) aluminum (Al), iron (Fe), calcium (Ca), sodium (Na), potassium (K), and magnesium (Mg)

34. Composition of continental crust Figure 2.16

35. ?????? How can it be that… oxygen (a gas) and silicon (a metalloid) are the #1 and #2 most abundant elements in the earth ’ s crust?

36. Minerals  Mineral groups Most common Rock-forming mineral group is the: Silicates Contain the silicon-oxygen tetrahedron (molecule) Four oxygen atoms surrounding a much smaller silicon atom

37. Silicon-oxygen tetrahedron (SiO 4 ) -4 molecule Figure 2.17

38. Minerals  Mineral groups Rock-forming silicates Combines with other atoms to form the various silicate structures Groups based upon tetrahedral arrangement Olivine – independent tetrahedra Pyroxene group – tetrahedra are arranged in chains Amphibole group – tetrahedra are arranged in double chains

39. Minerals  Mineral groups Rock-forming silicates Groups based upon tetrahedral arrangement Micas – tetrahedra are arranged in sheets Two types of mica are biotite (dark) and muscovite (light) Feldspars - Three-dimensional network of tetrahedra

40. Hornblende – a member of the amphibole group

41. Minerals  Mineral groups Rock-forming silicates Groups based upon tetrahedral arrangement Feldspars Two types of feldspar are Orthoclase and Plagioclase Quartz – three-dimensional network of tetrahedra

42. Three examples of perfect cleavage – fluorite, halite, and calcite

43. Conchoidal fracture Figure 2.15

44. Potassium feldspar

45. Plagioclase feldspar

46. Minerals  Mineral groups Rock-forming silicates Feldspars are the most plentiful mineral group Crystallize from molten material Nonsilicate minerals Major groups Oxides Sulfides

47. Minerals  Mineral groups Nonsilicate minerals Major groups Sulfates Carbonates “ Native ” elements

48. Native Copper

49. Minerals  Mineral groups Nonsilicate minerals Carbonates A major rock-forming group Found in the rocks limestone and marble Halite and gypsum are found in sedimentary rocks Many have economic value

50. Minerals  Mineral resources Reserves are already identified deposits Ores are useful metallic minerals that can be mined at a profit Economic factors may change and influence a resource

51. An underground halite (salt) mine

52. Mineral Gemstones A gemstone is defined as… Precious? semi-precious?

53. Tumbled “ Gems ” Stones

54. Gems are valued for their reflective properties due to the way they cut (facets).

55. Topaz Rough – uncut – unpolished

56. Malachite Raw formcut and polished

57. Turquoise Natural turquoisejewelry

58. Opal Raw form

59. End of Chapter 2