Earth materials

1. Earth materials
(part 1)
Dr.Krit Won-in
Department of Earth Sciences
Faculty of Science
Kasetsart University
[email protected]
081-633-5337

2. The
rock
cycle
Figure 1.21

3. Matter and Minerals

4. Minerals: Building blocks of rocks
•By definition a mineral is
•Naturally occurring
•Inorganic solid
•Ordered internal molecular structure
•Definite chemical composition
•Rock
•A solid aggregate of minerals

5. Structure of an atom
Figure 3.4 A

6. Composition of minerals
•Chemical bonding
•Formation of a compound by combining two
or more elements
•Ionic bonding
•Atoms gain or lose outermost (valence)
electrons to form ions
•Ionic compounds consist of an orderly
arrangement of oppositely charged ions

7. Halite (NaCl) – An example of ionic
bonding
Figure 3.6

8. Physical properties
of minerals
•Primary diagnostic properties
•Determined by observation or performing a
simple test
•Several physical properties are used to
identify hand samples of minerals

9. Physical properties
of minerals
•Crystal form
•External expression of a mineral’s internal
structure
•Often interrupted due to competition for
space and rapid loss of heat

10. A garnet crystal

11. Cubic crystals of pyrite
Figure 3.11 A

12. Physical properties
of minerals
•Luster
•Appearance of a mineral in reflected light
•Two basic categories
–Metallic
–Nonmetallic
•Other descriptive terms include vitreous, silky,
or earthy

13. Galena (PbS) displays metallic luster

14. Physical properties
of minerals
•Color
•Generally unreliable for mineral identification
•Often highly variable due to slight changes in
mineral chemistry
•Exotic colorations of certain minerals produce
gemstones

15. Quartz (SiO
2
) exhibits a variety of
colors
Figure 3.26

16. Physical properties
of minerals
•Streak
•Color of a mineral in its powdered form
•Hardness
•Resistance of a mineral to abrasion or
scratching
•All minerals are compared to a standard scale
called the Mohs scale of hardness

17. Streak is obtained on an unglazed
porcelain plate
Figure 3.12

18. Mohs scale
of
hardness
Figure 3.13

19. Physical properties
of minerals
•Cleavage
•Tendency to break along planes of weak
bonding
•Produces flat, shiny surfaces
•Described by resulting geometric shapes
–Number of planes
–Angles between adjacent planes

20. Common
cleavage
directions
Figure 3.15

21. Fluorite, halite, and calcite all exhibit
perfect cleavage

22. Physical properties
of minerals
•Fracture
•Absence of cleavage when a mineral is broken
•Specific Gravity
•Weight of a mineral / weight of an equal
volume of water
•Average value = 2.7

23. Conchoidal fracture
Figure 3.16

24. Physical properties
of minerals
•Other properties
•Magnetism
•Reaction to hydrochloric acid
•Malleability
•Double refraction
•Taste
•Smell
•Elasticity

25. Mineral groups
•Nearly 4000 minerals have been named
•Rock-forming minerals
•Common minerals that make up most of the
rocks of Earth’s crust
•Only a few dozen members
•Composed mainly of the 8 elements that make
up over 98% of the continental crust

26. Elemental abundances
in continental crust
Figure 3.18

27. Igneous Rocks

28. The
rock
cycle
Figure 1.21

29. General characteristics
of magma
•Igneous rocks form as molten rock cools
and solidifies
•General characteristics of magma
•Parent material of igneous rocks
•Forms from partial melting of rocks
•Magma at surface is called lava

30. General characteristics
of magma
•General characteristic of magma
•Rocks formed from lava = extrusive, or
volcanic rocks
•Rocks formed from magma at depth =
intrusive, or plutonic rocks

31. Evolution of magmas
•A single volcano may extrude lavas
exhibiting very different compositions
•Bowen’s reaction series
•Minerals crystallize in a systematic fashion
based on their melting points
•During crystallization, the composition of the
liquid portion of the magma continually
changes

32. Bowen’s reaction series
Figure 4.23

33. Assimilation, magma mixing, and
magmatic differentiation
Figure 4.25

34. Igneous compositions
•Naming igneous rocks – granitic rocks
•Granite
–Phaneritic
–Over 25% quartz, about 65% or more feldspar
–Very abundant - often associated with mountain
building
–The term granite includes a wide range of mineral
compositions
•Rhyolite
–Extrusive equivalent of granite
–May contain glass fragments and vesicles
–Aphanitic texture
–Less common and less voluminous than granite

35. Granite
Figure 4.9 A

36. Rhyolite
Figure 4.9 B

37. Igneous compositions
•Naming igneous rocks – intermediate rocks
•Andesite
–Volcanic origin
–Aphanitic texture
•Diorite
–Plutonic equivalent of andesite
–Coarse grained

38. Andesite
Figure 4.13

39. Diorite
Figure 4.14

40. Igneous compositions
•Naming igneous rocks – basaltic rocks
•Basalt
–Volcanic origin
–Aphanitic texture
–Composed mainly of pyroxene and calcium-rich
plagioclase feldspar
–Most common extrusive igneous rock
•Gabbro
–Intrusive equivalent of basalt
–Phaneritic texture consisting of pyroxene and
calcium-rich plagioclase
–Significant % of the oceanic crust

41. Basalt
Figure 4.15 A

42. Gabbro
Figure 4.15 B

43. Volcanoes and Other
Igneous Activity

44. Cinder cone volcano
Figure 5.14

45. Anatomy of a
composite volcano
Figure 5.9

46. Mt. St. Helens – prior
to the 1980 eruption

47. Mt. St. Helens after
the 1980 eruption

48. A nueé ardente on
Mt. St. Helens
Figure 5.20

49. A pahoehoe lava flow
Figure 5.5 A

50. Aa lava flow
Figure 5.5 B

51. Formation of a
volcanic neck
Figure 5.27

52. Shiprock, New Mexico

53. END of Part 1

54. Earth materials
(part 2)
Dr.Krit Won-in
Department of Earth Sciences
Faculty of Science
Kasetsart University
[email protected]
081-633-5337

55. Sedimentary Rocks

56. The
rock
cycle
Figure 1.21

57. What is a sedimentary rock?
• Sedimentary rocks are important for
economic considerations because they may
contain
•Coal
•Petroleum and natural gas
•Sources of iron, aluminum, and manganese

58. Sedimentary Process
1. Weathering 2. Erosion
and Transportation
3. Deposition
4. Diagenesis

59. Diagenesis
chemical, physical, and biological changes that take
place after sediments are deposited
•Occurs within the upper few kilometers of Earth’s crust
•Includes
–Recrystallization – development of more stable minerals
from less stable ones
–Lithification – sediments are transformed into solid rock
by
»Compaction and cementation
»Natural cements include calcite, silica, and iron oxide

61. Type of Sedimentary rocks
Clastic sediment
Size of sediment
Non-clastic sediment
Chemical sediment

62. Clastic sediment
Size of sediment

63. Shale with plant remains
Figure 7.2

64. Quartz sandstone
Figure 7.4

65. Conglomerate
Figure 7.6

66. Breccia
Figure 7.7

67. Coquina
Figure 7.9

68. Fossiliferous limestone

69. Stages
of
coal
formation
Figure 7.15

70. Stages
of
coal
formation
Figure 7.15

71. Non-clastic sediment
evaporites ,
carbonates and
siliceous rocks.

72. Evaporites - The evaporites form from the evaporation of
water (usually seawater).
Rock salt - composed of halite (NaCl).
Rock gypsum - composed of gypsum (CaSO4.2H20)
Travertine - composed of calcium carbonate (CaCO3), and
therefore, also technically a carbonate rock; travertine
forms in caves and around hot springs

73. Gypsum
Halite

74. Carbonates - The carbonate sedimentary rocks are formed through both chemical
and biochemical processes. They include the limestones (many types) and
dolostones.
Two minerals are dominant in carbonate rocks:
Calcite (CaCO3)
Dolomite (CaMg(CO3)2)
Remember which of these fizzes readily, and which of these must be
scratched or powdered!
Carbonate rock names:
Micrite (microcrystalline limestone) - very fine-grained; may be light gray
or tan to nearly black in color. Made of lime mud, which is also called
calcilutite.
Oolitic limestone (look for the sand-sized oolites)
Fossiliferous limestone (look for various types of fossils in a limestone
matrix)
Coquina (fossil hash cemented together; may resemble granola)
Chalk (made of microscopic planktonic organisms such as
coccolithophores; fizzes readily in acid)
Crystalline limestone
Travertine (see evaporites)
Others - intraclastic limestone, pelleted limestone

75. Limestone
Chalk

76. Siliceous rocks - The siliceous rocks are those which are dominated by silica (SiO2).
They commonly form from silica-secreting organisms such as diatoms, radiolarians,
or some types of sponges. Chert is formed through chemical reactions of silica in
solution replacing limestones.
Diatomite - looks like chalk, but does not fizz in acid. Made of microscopic
planktonic organisms called diatoms. May also resemble kaolinite, but is much
lower in density and more porous). Also referred to as Diatomaceous Earth.
Chert - Massive and hard, microcrystalline quartz. May be dark or light in color.
Often replaces limestone. Does not fizz in acid.

77. chert
diatomite

78. Metamorphism and
Metamorphic Rocks

79. The
rock
cycle
Figure 1.21

80. Metamorphism
•The transition of one rock into another by
temperatures and/or pressures unlike those
in which it formed
•Metamorphic rocks are produced from
•Igneous rocks
•Sedimentary rocks
•Other metamorphic rocks

81. Metamorphism
•Metamorphism progresses incrementally
from low-grade to high-grade
•During metamorphism the rock must
remain essentially solid
•Metamorphic settings
•Contact or thermal metamorphism – driven
by a rise in temperature within the host rock

82. Metamorphism
•Metamorphic settings
•Hydrothermal metamorphism – chemical
alterations from hot, ion-rich water
•Regional metamorphism
–Occurs during mountain building
–Produces the greatest volume of metamorphic
rock
–Rocks usually display zones of contact and/or
hydrothermal metamorphism

83. Pressure in metamorphism
Figure 8.4

84. Foliation resulting from directed
stress

85. Slate (left) and
phyllite (right)
Figure 8.14

86. Garnet-mica schist
Figure 8.11

87. Classifying metamorphic rocks
Figure 8.12

88. Contact metamorphism
Figure 8.19

89. Hydrothermal metamorphism
Figure 8.20

90. Marble
Figure 8.17

91. Quartzite
Figure 8.18

92. Metamorphic environments and plate
tectonics
Figure 8.28