Minerals, Rocks and the Rock Cycle

1
Minerals, Rocks and the Rock Cycle
2
What is a mineral?

• Occurs naturally
• Is a solid
• Definite chemical composition
• Atoms arranged in orderly pattern

3
May Be Elements or Compounds

• Native Minerals
• Form uncombined in nature
• Au, Ag, Cu, S, C
• Gold, silver, copper, sulfur, diamond
• Most are compounds
• Form from magma
• Form as evaporites
• Changed by heat, pressure, or water

4
Silicates

• 90 minerals on Earth
• Most common
• Si, O, and 1 or more metallic ions
• Si04
• Tetrahedron shape

5
Identifying Minerals

• Over 200 known
• Can be identified from physical properties

How can I tell what this is?
6
Identification Properties

• COLOR
• Least useful
• Many have similar colors
• Other elements may change color
• Beryl (emerald)?

7
Colors of Quartz
8
Identification Properties

• LUSTER
• The shine in reflected light

9
LUSTER

• Glassy
• Adamantine
• Greasy

10
Identification Properties

• CRYSTAL SHAPE
• Hard to find
• Must have room to grow
• Crystal Systems
• Cubic
• Orthorhombic
• Tetragonal
• Triclinic
• Hexagonal
• Monoclinic

11
CRYSTAL SHAPE
12
Identification Properties

• STREAK
• Color of its powder
• Does not change
• Metallic as dark as sample
• Nonmetallic white to colorless

Streak Plate ?
13
Identification Properties

• CLEAVAGE
• Tendency to split easily or break along flat
  surfaces
• Mica 1 direction
• FRACTURE
• Break on uneven surfaces
• Conchoidal - obsidian

14
Identification Properties

• HARDNESS
• Resistance to being scratched
• Mohs Scale of Hardness

15
Mohs Scale of Hardness

• 1 - Talc fingernail scratches it easily
• 2 - Gypsum fingernail scratches it
• 3 - Calcite copper penny just scratches it
• 4 - Fluorite steel knife scratches it easily
• 5 Apatite steel knife scratches it
• 6 Feldspar steel knife does not scratch it
  easily it scratches window glass

16
Mohs Scale of Hardness

• 7 Quartz hardest common mineral it scratches
  steel and hard glass easily
• 8 Topaz harder than any common mineral
• 9 Corundum it scratches topaz
• 10 Diamond hardest of all minerals

17
Special Identification Properties

• Fluorescence

18
Special Identification Properties

• Magnetism
• Magnetite

19
Special Identification Properties

• Taste
• This will quickly identify the mineral halite
  (salt). If you are new to this process you must
  use this one with caution, as you never know what
  the unknown may be.
• Often, you may need to resort to this method
  (until you more fully understand other
  identifying traits) to differentiate halite from
  calcite.
• If you do taste the sample (especially in a class
  environment) you should realize that it has been
  handled by and probably tasted by hundreds of
  others.

20
Rocks the Rock Cycle

• James Hutton uniformitarianism
• The present is the key to the past
• Geologic processes that happen today happened in
  the past
• Earths present physical features were formed by
  these processes

21
Rocks the Rock Cycle
22
(No Transcript)
23
(No Transcript)
24
Igneous Rocks
25
(No Transcript)
26
Igneous Rocks

• Formed by cooling hardening of magma
• Plutonic intrusive, forms underground
• Volcanic extrusive, forms on surface

• 2 kinds of magma
• high SiO2, light colored, thick, slow moving
• called felsic
• low SiO2, dark colored
• called mafic

27
Igneous Rocks

• Grain size and texture depends on how quick
  cooled
• Slow large crystals
• Fast small crystals

28
Igneous Rocks

• Grouped based on mineral composition
• Light granite
• Dark gabbro

29
(No Transcript)
30
(No Transcript)
31
Sedimentary Rock
32
Sedimentary Rock
33
Sedimentary Rock
34
Sedimentary Rock

• Form from sediments hardening into rock
• From pieces of other rocks clastic, sandstone,
  shale
• Precipitating out of a solution chemical,
  limestone, rock salt
• From remains of plants animals organic, coal,
  limestone

35
Conglomerate
36
Sandstone
37
Limestone
38
Shale
39
Sedimentary Rock

• Most formed under water, but also in
  deserts/dunes
• Cemented together by SiO2, CaCO3, or FeO

The Law of Superposition
40
Sedimentary Rock

• Some contain fossils

41
Sedimentary Rock
Almost all show strata (layers)
42
Sedimentary Rock
43
Sedimentary Rock

• Some show ripple marks or mud cracks

44
Metamorphic Rock

• changed by heat pressure
• From mountain building
• Contact with magma

45
Metamorphic Rock
46
Metamorphic Rock
47
Metamorphic Rock

• Shale ? slate ? schist (if more HP are added)
• Shale or granite ? gneiss
• Limestone ? marble

48
Metamorphic Rock
Shale to Slate Metamorphism
49
Metamorphic Rock
50
Marble
51
(No Transcript)