Rocks and Minerals

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Rocks and Minerals
2011-05-04 15:30:44
Physical Science Rocks Minerals Geosphere

Last Unit- Chap. 20
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    • DEF- The part of the earth consisting of the crust and outer mantle.
    • The Geosphere is made out of rocks.
  2. What are rocks made out of?
  3. Two characteristics that indicate the rate of crystalization and the conditions of formation in a metamorpshic rock?

    Where did the crystalization and formation take place?
    • Size
    • Type of mineral
    • Occured deep below the Earth's surface.
  4. What two factors matter when a rock is forming?
    Temperature and pressure
  5. _________ are the buidling blocks of rocks.
  6. _______ are the building blocks of minerals.
  7. How many known elements are there?
    112, many are rare
  8. What 8 elements make up 98% of Earth's entire mass?
  9. Are Earth's elements distriubuted evenly?
    Are lighter elements on the bottom, mid or top?
    No. Lighter elemernts are mostly disrtibuted in the mid-to-outer portion of the planet.
  10. What three sources of heat acted together to bring young Earth to it's melting point?
    Impact heating, gravitational contraction heating, and radioactive decay heating
  11. How did the Earth form, once chunks of all sizes accumulated and it heated into a molten state?
    +the influence of gravity, dense, heavy iron-rich material sank to Earth's center and less dense, silixon and oxygen-rick material rose twoard the surface.
  12. How does the core, mantle, and crust compare in density
    iron-rich core, less-dense rocky mantle, and even less dense rocky crust
  13. Crust is composed of [the lighter elements]:
    • O and (Si)!
    • Remember statistics, what does ! mean?
    • !!!!
  14. Earth's internal structures in order, from top to bottom:
    Crust, Mantle, Outer core, Inner core
  15. What is a mineral?
    a naturally formed, inorganic crystalline solid, composed of a deteminable and ordered arrangment of atoms with a specific chemical composition
  16. 3 major characteristics of a mineral:
    • Naturally formed
    • Inorganic
    • Crystaline solid
  17. What is a mineral composed of?
    An ordered arrangment of atoms with a specific chemical compostion.
  18. What does it mean to be a crystalline solid?
    the atoms [that makeup up a mineral] are always arranged in an orderly geometric pattern.

    • the same type of minerals will always have the same geometric arrangment of atoms
    • (minerals typically have a range of compositions, but that range has fixed limits)
  19. Inorganic:

    Hint: organic substances are almost always made by living things.
    • Inorganic: not made out of organic molecules
    • Organic: a subs. composition is dominated by CARBON, OXYGEN, AND HYDROGEN (must have all three)
  20. Amorphous
    • Solid, but no crystal structure
    • Ex. Obsidian, a glass formed in volanoes.
  21. Minerals are classified by their: (easy)
    Chemical composition: elements, and crystal structure
  22. What properties determine a mineral's crytal form, hardness, fracture/cleavage, color, and density?
    • Compoistion
    • Crystal Structure
    • Strength of Chemical Bonds
  23. Polymorphs minerals
    Composed of the same elements in the same proportions, but their atoms are arranged differently.
  24. Identifying a crsyal by crystal form is usually difficult for what reason?
    Well shaped crystals are rare in nature b/c of space constraints
  25. Mineral's hardness:
    A mineral's resitance to scratching
  26. Mohs scale of hardness is used to:
    • compare the hardness od different minerals.
  27. Why are some minerals harder than others?
    They have different chemical bonds-- the stronger the bond the harder the mineral.
  28. What makes a chemical bond stronger?
    • Highly charged ions--greater attraction.
    • Size of the atoms matters as well, small atoms and ions can pack smaller distance between one another (they attract one another with more force).

    Gold has large atoms and is soft as its atoms are loosely packed and bonded.
  29. Planes of weakness
    planes along which chemical bons are weak or few in numbers.
  30. Cleavage
    is the tendency for a mineral to break along such planes of weakness.
  31. Mienerals that have no planar alingment of bonds, cannot display cleave, and always _______.
  32. Is the type & degree of cleavage or fracture useful in identifying minerals?
    YES! Think of your lab.
  33. Color as an identifiable feature of a mineral, useful or not?
    Not reliable- most minerals either occur in a vaierty of color or can be colorless.
  34. A mineral's density is the ratio of its ___ to its ____.
    mass to its volume
  35. Rock-forming minerals
    A dozen minerals that make-up most of the rocks exposed at Earth's surface.
  37. Silicates
    Minerals that contain both silicon and oxygen as part of their chemical composition
  38. Non-silicates
    Minerals that do not contain the two elements silicon and oxygen
  39. Most common mineral group
    Make up 90% of Earth's crust
    Most also contain the rest of the 8 most common elements
  40. Minerals are formed by
  41. Crystallization
    The growth of crystalline solid froma liquid or gas.
  42. How does crystallization start?
    When atoms begin to bond with each other in a particular geometric pattern. Then more and more atoms bond to the microscopic crystal, repating the underlying pattern, until the crystal grows.

    Why do atoms begin doing this? Ask
  43. Minerals crystallize from two different sources:
    • Magma--molten rock
    • &from water solutions
  44. What is the name for rocks formed by magma and for those formed from water solutions?
    • igneous rocks- magma
    • sedimentary rocks- water solutions