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Pyroxene

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Pyroxene

  1. 1. III. Atoms, Elements and Minerals <ul><li>A. Changing scales to looking at the </li></ul><ul><li>elements of the earth and its crust ( 8 most common ) </li></ul><ul><li>B. Introduction to minerals that comprise rocks </li></ul><ul><li>( 11 most common ) </li></ul><ul><li>C. The silicate minerals ( 7 ) </li></ul><ul><li>D. Other important rock-forming minerals ( 4 ) </li></ul><ul><li>E. Mineral properties </li></ul>
  2. 2. A. Changing Scale : Zooming in from global view to atomic scale The crust is made of rocks > Rocks are made of minerals > … Quartz Biotite Feldspar
  3. 3. A. Changing Scale : Zooming in from global view to atomic scale Rocks are made of minerals > Minerals are made of atoms
  4. 4. Atoms and Elements <ul><li>Nucleus </li></ul><ul><ul><li>Protons </li></ul></ul><ul><ul><ul><li>+ Charge </li></ul></ul></ul><ul><ul><ul><li>Has Mass, Atomic # </li></ul></ul></ul><ul><ul><li>Neutrons </li></ul></ul><ul><ul><ul><li>0 Charge </li></ul></ul></ul><ul><ul><ul><li>Mass same as One Proton </li></ul></ul></ul><ul><ul><ul><li>Atomic Mass # </li></ul></ul></ul><ul><li>Electrons </li></ul><ul><ul><li>In shells (2, 8, 8…) </li></ul></ul><ul><ul><li>- charge (balances each proton +) </li></ul></ul><ul><ul><li>Very little Mass </li></ul></ul>Electron Shells
  5. 5. Ions <ul><li>Incomplete electron shells tend to be filled </li></ul><ul><li>E.g. Chlorine (Cl - ) </li></ul><ul><ul><li>17 protons (at.# 17) </li></ul></ul><ul><ul><li>17 electrons would make it neutral (no charge) with the last shell one electron short {2, 8, 7 } Soooo… </li></ul></ul><ul><ul><li>Tends to grab an electron to fill the third shell </li></ul></ul><ul><ul><li>Making it a negatively charged Ion (anion) </li></ul></ul>
  6. 6. Ions <ul><li>Other Common Examples </li></ul><ul><ul><li>Sodium, at.# 11 {2, 8, 1 }  Na + </li></ul></ul><ul><ul><li>Oxygen, at.# 8 {2, 6 },  O -2 </li></ul></ul><ul><ul><li>Silicon, at.# 14 {2,8,4}  Si +4 </li></ul></ul>(Cation) Oxygen Sodium
  7. 8. Most Common Elements of Earth’s Crust Oxygen: O -2 Silicon: Si +4 Aluminum: Al +3 Iron: Fe +2 or +3 Calcium: Ca +2 Sodium: Na +1 Potassium: K +1 Magnesium: Mg +2
  8. 9. B. Introduction to Minerals <ul><li>Halite (Rock Salt) </li></ul><ul><ul><li>Mineral mined for rock salt and table salt </li></ul></ul><ul><ul><li>Na gives electron to Cl </li></ul></ul><ul><ul><li>Opposites attract, elements bond </li></ul></ul><ul><ul><li>NaCl (Sodium Chloride) </li></ul></ul>
  9. 10. Intro to Minerals <ul><li>Repeating 3-D pattern forms a Crystalline Solid (or Crystal ) </li></ul><ul><li>Naturally occurring crystals are Minerals </li></ul><ul><li>Crystalline structure and bonding leads to physical properties: hardness, crystal form, cleavage  specific gravity (density) (pg. 38-43) </li></ul>Crystal Form  3 planes of cleavage
  10. 11. <ul><li>Quartz Crystal </li></ul><ul><li>(SiO 2 ) </li></ul><ul><li>Snow Flake (Ice Crystal) due to crystalline structure of H 2 O </li></ul>Some Familiar Crystal Forms Fig. 2.15a
  11. 12. Silica Tetrahedra <ul><li>The building block of most common rock forming minerals </li></ul><ul><ul><li>Four O 2- in a tetrahedral configuration </li></ul></ul><ul><ul><li>One Si 4+ nested in the center </li></ul></ul><ul><ul><li>(4  -2 ) +4 = -4 </li></ul></ul><ul><ul><li>( Si O 4 ) -4 </li></ul></ul>
  12. 13. Silica Tetrahedra <ul><li>The building block of most common rock forming minerals </li></ul><ul><ul><li>Four O 2- in a tetrahedral configuration </li></ul></ul><ul><ul><li>One Si 4+ nested in the center </li></ul></ul><ul><ul><li>(4  -2 ) +4 = -4 </li></ul></ul><ul><ul><li>( Si O 4 ) -4 </li></ul></ul>
  13. 14. Silica Tetrahedra <ul><li>The building block of most common rock forming minerals </li></ul><ul><ul><li>Four O 2- in a tetrahedral configuration </li></ul></ul><ul><ul><li>One Si 4+ nested in the center </li></ul></ul><ul><ul><li>(4  -2 ) +4 = -4 </li></ul></ul><ul><ul><li>( Si O 4 ) -4 </li></ul></ul>
  14. 15. Silica Tetrahedra <ul><li>The building block of most common rock forming minerals </li></ul><ul><ul><li>Four O 2- in a tetrahedral configuration </li></ul></ul><ul><ul><li>One Si 4+ nested in the center </li></ul></ul><ul><ul><li>(4  -2 ) +4 = -4 </li></ul></ul><ul><ul><li>( Si O 4 ) -4 </li></ul></ul>
  15. 16. Silica Tetrahedra <ul><li>The building block of most common rock forming minerals </li></ul><ul><ul><li>Four O 2- in a tetrahedral configuration </li></ul></ul><ul><ul><li>One Si 4+ nested in the center </li></ul></ul><ul><ul><li>(4  -2 ) +4 = -4 </li></ul></ul><ul><ul><li>( Si O 4 ) -4 </li></ul></ul>
  16. 17. Silica Tetrahedra <ul><li>The building block of most common rock forming minerals </li></ul><ul><ul><li>Four O 2- in a tetrahedral configuration </li></ul></ul><ul><ul><li>One Si 4+ nested in the center </li></ul></ul><ul><ul><li>(4  -2 ) +4 = -4 </li></ul></ul><ul><ul><li>( Si O 4 ) -4 </li></ul></ul>
  17. 18. Silica Tetrahedra <ul><li>The building block of most common rock forming minerals </li></ul><ul><ul><li>Four O 2- in a tetrahedral configuration </li></ul></ul><ul><ul><li>One Si 4+ nested in the center </li></ul></ul><ul><ul><li>(4  -2 ) +4 = -4 </li></ul></ul><ul><ul><li>( Si O 4 ) -4 </li></ul></ul>
  18. 19. Silica Tetrahedra <ul><li>The building block of most common rock forming minerals </li></ul><ul><ul><li>Four O 2- in a tetrahedral configuration </li></ul></ul><ul><ul><li>One Si 4+ nested in the center </li></ul></ul><ul><ul><li>(4  -2 ) +4 = -4 </li></ul></ul><ul><ul><li>( Si O 4 ) -4 </li></ul></ul>-4
  19. 20. <ul><li>Naturally Occurring </li></ul><ul><li>Crystalline </li></ul><ul><li>Solid </li></ul><ul><li>With a definite chemical composition </li></ul><ul><ul><li>A unique composition </li></ul></ul><ul><ul><li>or </li></ul></ul><ul><ul><li>A definite range of compositions Mineral Group , e.g. Olivine </li></ul></ul>Definition of Mineral
  20. 21. C. Silica Tetrahedra and Silicate Minerals <ul><li>Si and O bond in a tetrahedron shape </li></ul><ul><li>The basic building block of most minerals of the crust </li></ul><ul><li>Bond with other tetrahedra and cations to form Silicate Minerals </li></ul>* *
  21. 22. Silicate Minerals: Examples <ul><li>E.g., Olivine </li></ul><ul><ul><li>Isolated silicate </li></ul></ul><ul><ul><li>structure </li></ul></ul><ul><ul><li>(SiO 4 ) -4 + 2 × Fe +2 </li></ul></ul><ul><ul><li>Fe 2 SiO 4 </li></ul></ul><ul><ul><li>Fe Mg SiO 4 </li></ul></ul><ul><ul><li>Mg 2 SiO 4 </li></ul></ul><ul><li>(Fe,Mg) 2 SiO 4  Olivine Mineral Group </li></ul>Definite Range
  22. 23. Silicate Minerals: Examples <ul><li>E.g., Olivine </li></ul><ul><ul><li>Isolated silicate structure </li></ul></ul><ul><ul><li>bonded with iron and magnesium </li></ul></ul><ul><ul><li>Makes up much of the mantle </li></ul></ul><ul><ul><li>Fe/Mg rich >50% </li></ul></ul><ul><ul><li>Silica poor <45% </li></ul></ul>*
  23. 24. Silicate Minerals: Examples <ul><li>E.g., Pyroxenes (Mineral Group) </li></ul><ul><ul><li>Single Chain Silicate structure </li></ul></ul><ul><ul><li>(SiO 3 ) -2 + Fe +2 </li></ul></ul><ul><ul><li>FeSiO 3 </li></ul></ul><ul><ul><li>(Fe,Mg) SiO 3 </li></ul></ul><ul><ul><li>MgSiO 3 </li></ul></ul><ul><ul><li>(Fe,Mg) SiO 3  Pyroxene </li></ul></ul><ul><ul><ul><li>Mineral Group </li></ul></ul></ul><ul><ul><ul><li>Ferromagnesian </li></ul></ul></ul>
  24. 25. Silicate Minerals: Examples <ul><li>E.g., Pyroxenes (Group of minerals) </li></ul><ul><ul><li>Single Chain Silicate structure </li></ul></ul><ul><ul><li>bonded with Fe, Mg , Ca, and Al </li></ul></ul><ul><ul><li>Found in Oceanic Crust </li></ul></ul><ul><ul><li>Fe/Mg/Ca rich (20%) </li></ul></ul><ul><ul><li>Silica poor (<20%) </li></ul></ul>
  25. 26. Building Silicates <ul><li>What is the net charge of: </li></ul><ul><ul><li>a silica tetrahedron? </li></ul></ul><ul><ul><li>a single chain of single tetrahedra? </li></ul></ul><ul><li>*Hint: a shared apex is ½ an Oxygen </li></ul>
  26. 27. Building Silicates <ul><li>What is the net charge of: </li></ul><ul><ul><li>a silica tetrahedron? </li></ul></ul><ul><ul><li>a single chain of single tetrahedra? </li></ul></ul><ul><ul><li>a double chain of tetrahedra? </li></ul></ul><ul><ul><li>a sheet of tetrahedra? </li></ul></ul><ul><ul><li>a framework of tetrahedra? </li></ul></ul><ul><ul><li>a framework of tetrahedra with every fourth silicon replaced with an aluminum ion? </li></ul></ul><ul><ul><li>a framework with every other Si replaced with an Al? </li></ul></ul><ul><li>*Hint: a shared apex is ½ an Oxygen </li></ul>
  27. 28. Building Silicates <ul><li>What common elements would balance the charges of : </li></ul><ul><ul><li>an isolated silicate? </li></ul></ul><ul><ul><li>a single chain silicate? </li></ul></ul><ul><ul><li>a double chain silicate? </li></ul></ul><ul><ul><li>a sheet silicate? </li></ul></ul><ul><ul><li>a framework silicate? </li></ul></ul><ul><ul><li>a framework of tetrahedra with every fourth silicon replaced with an aluminum ion? </li></ul></ul><ul><ul><li>a framework with every other Si replaced with an Al? </li></ul></ul>
  28. 29. Silicate Minerals: Examples <ul><li>E.g., Pyroxenes (Group of minerals) </li></ul><ul><ul><li>Single Chain Silicate structure </li></ul></ul><ul><ul><li>bonded with Fe, Mg , Ca, and Al </li></ul></ul><ul><ul><li>Found in Oceanic Crust </li></ul></ul><ul><ul><li>Fe/Mg/Ca rich </li></ul></ul><ul><ul><li>Silica poor </li></ul></ul>*
  29. 30. Single Chain Silicates <ul><li>E.g., Pyroxenes (SiO 3 ) </li></ul>
  30. 31. Silicate Minerals: Examples <ul><li>E.g., Amphiboles (Group of minerals) </li></ul><ul><ul><li>Double Chain Silicate structure </li></ul></ul><ul><ul><li>bonded with Fe, Mg, Ca, and Al </li></ul></ul><ul><ul><li>Found in Continental Crust </li></ul></ul><ul><ul><li>More silica and less iron than pyroxenes </li></ul></ul>*
  31. 32. Double Chain Silicates <ul><li>E.g., Amphiboles (Si 8 O 22 ) </li></ul>
  32. 33. Silicate Minerals: Examples <ul><li>E.g., Micas (Muscovite and Biotite) </li></ul><ul><ul><li>Sheet Silicate structure </li></ul></ul><ul><ul><li>bonded with Al , K, </li></ul></ul><ul><ul><ul><li>(biotite has Fe, Mg ) </li></ul></ul></ul><ul><ul><li>Found in Continental Crust </li></ul></ul><ul><ul><li>More silica and less iron than Amphiboles </li></ul></ul><ul><li>E.g., Clays (Mineral Group) </li></ul><ul><ul><li>Hydrated, sheet silicates from weathering of other silicates </li></ul></ul>*
  33. 34. Sheet Silicates <ul><li>E.g., Micas (Biotite and Muscovite) ( Al Si 3 O 10 ) </li></ul>
  34. 35. Silicate Minerals <ul><li>E.g., Feldspars (Orthoclase and Plagioclase) and Quartz </li></ul><ul><ul><li>Framework Silicate </li></ul></ul><ul><ul><li>bonded with Al , and K (orthoclase) or Na-Ca (plagioclase) </li></ul></ul><ul><ul><li>Found in Continental Crust </li></ul></ul><ul><ul><li>More silica than micas, no iron </li></ul></ul>Granite Orthoclase Quartz *
  35. 36. Framework Silicates <ul><li>E.g., Quartz ( SiO 2 ) and Feldspars (AlSi 3 O 8 ) </li></ul>
  36. 37. Framework Silicates <ul><li>E.g., Quartz ( SiO 2 ) and Feldspar ( Al Si 3 O 10 ) </li></ul>

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