1. Minerals
What is a Mineral?

2. Enduring Understanding
Minerals are the building blocks of rocks.

3. Minerals
Earth’s crust is composed of about 3,000 different minerals. They play very important roles in civilization. Throughout history wars have been waged and empires have risen and fallen over the conquest of a select few minerals such as gold and silver considered to be precious.

4. Mineral Characteristics
Mineral is a naturally occurring, inorganic solid with a specific chemical composition and a definite crystalline structure
Naturally Occurring means they are formed by natural processes

5. Mineral Characteristics
Synthetic diamonds and other materials developed in labs are not minerals

6. Mineral Characteristics
Inorganic means that they are not and never were alive
Salt is a mineral sugar is not

7. Mineral Characteristics
Solid means it has a definite shape and volume
No liquids or gases
can be minerals!!!

8. Mineral Characteristics
Specific Chemical Composition means that since most minerals are compounds, the elements and their proportions are unique to that mineral
The chemical composition for Quartz is SiO2, with a chemical breakdown of approximately 46.7% silicon and 53.3% oxygen.  Quartz is easily transformed from low to high quartz at 573 degrees Celsius with only minor atomic adjustments and without breaking any of the Si-O bonds.

9. Mineral Characteristics
Some minerals such as silver are found as a single element

10. Mineral Characteristics
Definite Crystalline Structure means the atoms are arranged in regular geometric patterns that are repeated over and over.
There are six major crystal systems:

11. Cubic

12. Tetragonal

13. Hexagonal
Beryl

14. Orthorhombric
Olivine

15. Monoclinic
Amphibole

16. Triclinic
Turquoise

17. Mineral Formation
Since minerals must form from natural processes there are two primary ways that they form here on Earth

18. Mineral Formation
Minerals can form from the cooling of magma which is the molten material found beneath Earth’s surface as magma rises closer to the surface the molten compounds no longer move freely and they begin to interact chemically to form minerals

19. Mineral Formation
Small crystals means the magma cooled rapidly

20. Mineral Formation
Large crystals means the magma cooled more slowly

21. Mineral Formation
Minerals also form from solution such as when a liquid evaporates from the solution and the elements remain behind “Evaporites”

22. Mineral Formation
Minerals will precipitate (drop out) of a solution that becomes supersaturated meaning it can hold no more dissolved solids

23. Mineral Groups
Of the 3,000 minerals found in the crust only about 30 of these are common. Ten of these make up about 90% of the Earth’s crust

24. Mineral Groups
Silicates are the most abundant group (96%) containing the two most abundant elements in the crust Silicon (Si) and Oxygen (O)

25. Mineral Groups
Quartz and Feldspar are the most abundant minerals

26. Mineral Groups
Carbonates are minerals composed of one or more metallic elements with the carbonate compound CO3

27. Mineral Groups
Calcite and dolomite are common examples

28. Mineral Groups
Carbonates are the primary minerals in rocks such as limestone, coquina, and marble

29. Mineral Groups Oxides are compounds of oxygen (O) and a metal.
Hematite (Fe2O3) and Magnetite (Fe3O4) are common examples

30. Igneous Rocks

31. Endurung Understanding
The rock cycle is an ongoing process by which rocks are formed. It gives us an explanation of how Earth materials are recycled through time.
Virginia has many natural resources.

32. Igneous Rocks
Minerals combine in the Earth’s crust to form rocks. Most rocks are made of one or more minerals. Igneous rocks were the first type to form on Earth as its molten surface cooled and solidified

33. Igneous Rocks
Igneous Rocks form from the crystallization of magma

34. Igneous Rocks
Magma is molten rock below Earth’s surface

35. Igneous Rocks
Lava is magma that flows out onto Earth’s surface

36. Igneous Rock Types
Igneous rocks are classified based upon where they form
Extrusive igneous rocks cool quickly on the surface and are fine-grained (small crystals)

37. Igneous Rock Types
Rhyolite is the most common extrusive igneous rock

38. Igneous Rock Types Pumice Obsidian Basalt
Other common extrusive igneous rocks include pumice, obsidian, and basalt
Pumice
Obsidian
Basalt

39. Igneous Rock Types
Intrusive igneous rocks cool slowly beneath the surface and are coarse-grained (larger crystals)

40. Igneous Rock Types
Granite is the most common intrusive igneous rock

41. Magma
Magma is often a slushy mix of molten rock, gases and mineral crystals. The elements in magma are the same major elements found in the Earth’s crust: oxygen (O), silicon (Si), aluminum (Al), iron (Fe), magnesium (Mg), calcium (Ca), potassium (K), and sodium (Na)

42. Magma
Silica (SiO2) is the most common compound in magma and has the greatest effect on its characteristics
Rhyolitic magma has an SiO2 content of 70%
Andesitic magma has an SiO2 content of 60%
Basaltic magma has an SiO2 content of 50%

43. Magma Formation
There are four main factors that affect magma formation
Temperature. Heat comes from the remaining energy from Earth’s formation and the decay of radioactive elements

44. Magma Formation
There are four main factors that affect magma formation
Pressure. The pressure increases with depth

45. Magma Formation
There are four main factors that affect magma formation
Water content. More decreases the melting point of the rocks

46. Magma Formation
Mineral content. Minerals melt at different temperatures

47. Classifying Igneous Rocks
Extrusive and intrusive igneous rocks are further classified by their mineral compositions

48. Classifying Igneous Rocks
Felsic rocks are light colored, have high silica contents, and contain quartz and the feldspars orthoclase and plagioclase
Granite is the most common felsic rock

49. Classifying Igneous Rocks
Intermediate rocks are darker than felsic and have moderate amounts of biotite, amphibole, and pyroxene
Diorite is a good example of an intermediate rock

50. Classifying Igneous Rocks
Mafic rocks are dark, have lower silica contents and are rich in iron and magnesium
Basalt is a mafic rock

51. Classifying Igneous Rocks
Ultramafic rocks have low silica contents and very high levels of iron and magnesium.
Olivine is an ultramafic rock

52. Bowen’s Reaction Series
As magma cools, minerals form in predictable patterns. The reaction series has two main branches of crystallization

53. Bowens Reaction Series

54. Bowen’s Reaction Series
As minerals form in the order shown in Bowens reaction series elements are removed from the remaining magma. Silica and Oxygen are the most abundant elements and are left over at the end of the reaction series. The remaining magma finally crystallizes to form quartz.

55. Bowens Reaction Series

56. Sedimentary Rocks

57. Objective 2. Classify sedimentary rocks by texture and composition.
Clastic – sandstone, conglomerate, and shale;
nonclastic – limestone and rock salt.

58. Sedimentary Rocks
The second classification of rocks includes many of the common types seen on the Earth’s surface. The native rocks found here on the coastal plain of Virginia are mostly of the sedimentary variety

59. Sedimentary Rocks
Sediments are pieces of solid material that have been deposited on the surface by wind, water, ice, gravity or chemical precipitation

60. Sedimentary Rocks
Sediments are eroded and transported to new locations by four main agents: Wind, moving water, gravity, and glaciers

61. Sedimentary Rocks
Deposition occurs when sediment transport ceases and they are laid down on the ground or sink to the bottom of water
Sedimentary deposits are then buried in layers called sedimentary basins from oldest to youngest
These basins can be as much as 8 km thick

62. Classification of clastic sediments
The sediments that form rocks can be classified according to the size of their particles
> 2mm – Gravel
0.062mm - 2mm – Sand
0.0039mm mm – Silt
< .0039mm - Clay

63. Lithification
Lithification occurs as the temperature and pressure increases in the buried sediment and the physical and chemical processes transform the sediment into sedimentary rock

64. Lithification
The temperature in the crust increases by about 30 degrees per kilometer

65. Lithification
Cementation occurs when mineral growth cements sediment grains together into solid rock

66. Types of Sedimentary rocks
The classification of sedimentary rocks is based on how they were formed. There are 3 main groups of sedimentary rocks

67. Types of Sedimentary rocks
Clastic sedimentary rocks are formed from the lithification of abundant deposits of loose sediments found on the Earth’s surface

68. Types of Sedimentary rocks
They can further be classified according to their particle size
Course-grained clastics consist of gravel-sized rock and mineral fragments

69. Types of Sedimentary rocks
Conglomerate and breccia are examples

70. Types of Sedimentary rocks
Medium-grained clastics consist of sand-sized particles
Sandstone is a medium-grained clastic rock

71. Types of Sedimentary rocks
Fine-grained clastics are made of silt and clay sized particles
Shale is an example

72. Types of Sedimentary rocks
Chemical sedimentary rocks form through processes such as evaporation when bodies of water become oversaturated with solids.

73. Types of Sedimentary rocks
Crystal grains will precipitate out of the solution and settle to the bottom to form layers of chemical sedimentary called evaporites

74. Types of Sedimentary rocks
Rock salt is formed this way and the main source of the table salt we use every day

75. Types of Sedimentary rocks
Organic sedimentary rocks are formed from the remains of once-living things.

76. Types of Sedimentary rocks
These rocks form in the oceans and as the organisms die their shells settle to the bottom form thick layers of sediment over geologic time.

77. Types of Sedimentary rocks
Eventually these layers of sediment can undergo lithification and become solid rock

78. Types of Sedimentary rocks
Limestone is our most common organic sedimentary rock

79. Types of Sedimentary rocks
Coal forms when the remains of plant material accumulate in swamps and coastal areas. These layers are buried and compressed over millions of years and become lithified

80. Metamorphic Rocks

81. Objective 3. Classify metamorphic rocks by texture and composition.
Foliated – slate, schist, and gneiss;
Nonfoliated – marble and quartzite.

82. Metamorphic Rocks
When high pressure and temperature combine to alter the texture, mineralogy, or chemical composition of a rock without actually melting it, then the third classification of rocks form metamorphic

83. Metamorphic Rocks
During metamorphism the rock changes while remaining in the solid form

84. Metamorphic Rocks
The temperatures required come from Earth’s internal heat

85. Metamorphic Rocks
The high pressures required can be generated from either vertical pressure from the overlying rock or from the compressive forces as rocks are deformed

86. Types of Metamorphism
Different combinations of temperature and pressure result in different types of metamorphism

87. Types of Metamorphism
Regional metamorphism occurs when high temperature and pressure affect large regions of the crust

88. Types of Metamorphism
Plate movements and mountain-building results in regional metamorphism

89. Types of Metamorphism
Contact metamorphism occurs when molten rocks come in contact with solid rock.

90. Types of Metamorphism
An igneous intrusion causes many instances of contact metamorphism

91. Types of Metamorphism
Hydrothermal metamorphism occurs when very hot water reacts with rock and alters its chemistry and mineralogy

92. Types of Metamorphism
Yellowstone National Park gets its name from this type of geologic activity

93. Metamorphic Textures
Foliated metamorphic rocks have wavy layers and bands of minerals

94. Metamorphic Textures
Slate, schist (shale) and gneiss (granite) are the two most common types

95. Metamorphic Textures
Nonfoliated metamorphic rocks are composed of minerals that form with blocky crystal shapes; no layers and bands

96. Metamorphic Textures
Quartzite (sandstone) and Marble (limestone) are common examples

97. The Rock Cycle
Rocks are not as immortal as one may think. The three rock classifications igneous, sedimentary, and metamorphic are constantly changing under the geologic conditions and recycling themselves becoming other forms

98. The Rock Cycle
Igneous rocks break down under chemical and physical weathering on the surface to form sediment that can then undergo lithification and form sedimentary rock.

99. The Rock Cycle
Any rocks that melt again become igneous rocks and may re-crystallize in a completely different combination of minerals.

100. The Rock Cycle

101. The Physiographic Provinces of Virginia
Virginia has had a long, complex geologic history, over 1.1 billion years
Events that have led to the formation of a rich diversity of rocks, and events that have folded, faulted and rearranged those rocks in complex patterns.
A physiographic province is a landform region, areas divided according to similar terrain that has been shaped by a common geologic history.
Geographers recognize more than 20 physiographic provinces in North America; five of these are in the state of Virginia.

102. The Physiographic Provinces of Virginia
Each province is characterized overall by its elevation, relief, lithology, and geologic structure. Because of the region’s history of rock formation, deformation, and erosion, specific types of landforms or other geologic features may be associated with a given province.

103. The Physiographic Provinces of Virginia

104. Coastal Plain
The Coastal Plain is a flat area underlain by young, unconsolidated sediments.
Includes all of Virginia East of the Fall Line.
The Fall Line is where Rivers cross from the hard igneous and metamorphic rocks of the Piedmont onto the soft roundest rocks in Virginia.
Deposits of sand, silt and clay including marine fossils deposited by rivers.
Layers of sediment were produced by erosion of the Appalachian Mountains and then deposited on the Coastal Plain.

105. Coastal Plain

106. Piedmont
The Piedmont is an area of rolling hills underlain by mostly ancient igneous and metamorphic rocks.
Igneous rocks are the roots of volcanoes formed during an ancient episode of subduction that occurred before the formation of the Appalachian Mountains.
Largest physiographic province.
Bounded on the east by the Fall Zone, and on the west by the mountains of the Blue Ridge.
Rolling topography, deeply weathered bedrock and rocks are strongly weathered.
Rocks are generally buried under a thick (2-20m) blanket of saprolite. ( a chemically weathered rock)
Topography is more rugged closer to the Blue Ridge.

107. Piedmont

108. Blue Ridge
The Blue Ridge is a high ridge of crystalline rock separating the Piedmont from the Valley and Ridge Province.
The billion-year old igneous and metamorphic rocks of the Blue Ridge are the oldest in the state.
The Blue Ridge province experienced mountain building during the late Neoproterozoic era ( Ma).
In central and northern Virginia, the 570 million year old basalts are over sedimentary rock.
Some metamorphism of these rocks occurred during the formation of the Appalachian Mountains.

109. Blue Ridge

110. Valley and Ridge
Long parallel ridges and valleys of sedimentary rock which were folded and faulted, and eroded differently.
540 million years old sandstones are overlain by carbonates that make up a region of limestone and dolomite.
The folding and faulting of the sedimentary rocks occurred during a collision between Africa and North America.
The collision, which occurred in the late Paleozoic, produced the Appalachian Mountains.
Carbonates were deposited in a shallow tropical ocean along the southeast edge of North America.
Carbonates in the Shenandoah Valley create the correct environment for caves and sinkholes (Karst Topography)

111. Valley and Ridge

112. Appalachian Plateau
The Appalachian Plateau has rugged irregular topography and is underlain by ancient, flat-lying sedimentary rocks.
Large folds of rock found in the Valley and Ridge become smaller folds and flat-lying rocks in the Plateau.
Some parts of the Plateau are relatively flat, and some are hilly and rugged.
The area is actually a series of plateaus separated by faults. The upper layers of the Plateau are rich in mineral resources like coal, natural gas, and petroleum.

113. Appalachian Plateau