2Chapter: Earth Materials Table of ContentsChapter: Earth MaterialsSection 1: MineralsSection 2: Igneous RocksSection 3: Sedimentary RocksSection 4: Metamorphic Rocks and the Rock Cycle
3Composition of Earth’s Crust Minerals1Common ElementsComposition of Earth’s CrustThe crust is the outermost layer of Earth.
4Minerals1What’s a Mineral?A mineral is a naturally occurring element or compound that is inorganic, solid, and has a crystalline structure.
5Minerals1Physical PropertiesA mineral has a characteristics set of physical properties, but some of these properties can differ from sample to sample.
6Minerals1Atom ArrangementSome physical properties are controlled by the orderly arrangement of atoms in a mineral’s structure.The arrangement of atoms and the bonds between them can reflect the way a mineral breaks, how hard it is, and what types of crystal shape it has.
7Minerals1Atom ArrangementMinerals break along planes that cut across relatively weak chemical bonds, a smooth, flat surface is created. This is called cleavage.Some minerals do not split along well-defined flat surfaces. In such cases, a mineral will break unevenly. This type of irregular break is called fracture.
8Minerals1HardnessThe physical property that measures resistance to scratching is called hardness.
9Minerals1Luster and StreakThe way a mineral reflects light is the physical property known as luster.Metallic and nonmetallic.Metallic luster minerals reflect light in a way that a metal surface might.
10Minerals1Luster and StreakNonmetallic luster, includes minerals that shine like glass or appear earthy or waxy.The color of mineral in powdered form is called streak.
11Minerals1Crystal ShapeThe orderly internal arrangement of atoms in a mineral often is indicated by its external crystal shape.The types of symmetry shown by the crystal are key elements in determining the crystal system to which a mineral belongs.
12Minerals1Mineral FormationGrowth also is controlled by how fast atoms can migrate to the crystal and by the temperature and pressure conditions of the surroundings.
13Minerals From Hot Water 1Minerals From Hot WaterSome minerals are produced from hot water solutions rich in dissolved mineral matter.When hot water passes through cracks in cooler rock, minerals may form within the cracks.
14Minerals1Minerals from MagmaMolten rock material found inside Earth is called magma.As magma cools, atoms slow down and begin to arrange into an orderly structure.Below the solidification temperature of a mineral, crystals of that particular mineral may form and grow.
15Minerals From Evaporation 1Minerals From EvaporationWhen water slowly evaporates, concentrated dissolved mineral may be left behind to form crystal.
16Mineral Groups Silicates 1 Minerals1Mineral GroupsSilicatesSilica is a common term for a compound that contains silicon plus oxygen or silicon dioxide (SiO2).
17Minerals1Silicate StructuresThe simplest silicate structures have silicon-oxygen tetra-hedrons that are not linked together.By joining silicon-oxygen tetrahedrons together, chains, sheet, and three-dimensional framework structures can form.
18Minerals1Silicate StructuresQuartz and feldspar group silicates make up most of Earth’s continental crust.Earth’s oceanic crust is denser and contains a larger percentage of silicates whose tetrahedrons are not linked together as much.
19Important Non-silicates Minerals1Important Non-silicatesMany important mineral groups are not silicates.These include the carbonates, oxides, halides, sulfides, sulfates, and native metals.The non-silicate groups are a source of many valuable ore minerals and building materials.
20Important Non-silicates Minerals1Important Non-silicatesTo be an ore, a mineral must occur in large enough quantities to be economically recoverable.
21Question 1 1 Which is NOT a mineral? A. apatie B. flourite C. gold Section Check1Question 1Which is NOT a mineral?A. apatieB. flouriteC. goldD. oxygen
22Section Check1AnswerThe answer is D. A mineral must be a solid.
23Question 2 1 Which is NOT a physical property of minerals? A. cleavage Section Check1Question 2Which is NOT a physical property of minerals?A. cleavageB. fractureC. hardnessD. Mohs
24Section Check1AnswerThe answer is D. Mohs is a scale used to determine the hardness of a mineral.
25Question 3 1 How many crystal shapes have been identified? A. five Section Check1Question 3How many crystal shapes have been identified?A. fiveB. sixC. sevenD. eight
26Section Check1AnswerThe answer is B. Minerals can be classified by these six shapes.
27Igneous Rocks2What’s a rock?A rock is a naturally formed consolidated mixture containing minerals, rock fragments, or volcanic glass.Rocks are identified by their composition and texture.Texture is a description that includes the size and arrangement of the rock’s components.
28Intrusive Igneous Rocks 2Intrusive Igneous RocksIgneous rocks are those that form from molten rock material called magma.Such rocks also are called intrusive igneous rocks because they form within, or push into, regions of Earth’s crust.
29Igneous Rocks2Nature of MagmaAs it passes through rock, magma might cause partial melting of the rock it intrudes.Geologists have learned that minerals melt at different temperatures, so some will melt when exposed to the thermal energy of the magma.
30Igneous Rocks2Nature of MagmaAs crystals solidify in cooling magma, they use up certain atoms.High-temperature magmas tend to crystallize first.
31Nature of Magma 2 Late-forming, less dense minerals tend Igneous Rocks2Nature of Magmato solidify at lower temperatures and float to the top of the magma chamber.Late-forming, less dense minerals tend
32Igneous Rocks2Nature of MagmaThe composition of intrusive igneous rocks gives you clues as to where in Earth they formed.Igneous rocks with abundant quartz generally are associated with continental crust.Those with little or no quartz generally are associated with deep locations in continental crust or with oceanic crust.
33Intrusive Igneous Rock Texture Igneous Rocks2Intrusive Igneous Rock TextureIn intrusive igneous rocks, grain size, which means the size of individual mineral crystals, gives you clues as to how fast magma cooled.Magma that cools slowly, allows atoms time to migrate about and form large crystals.
34Classification of Intrusive Igneous Rocks 2Classification of Intrusive Igneous RocksRocks that are quartz-rich and contain potassium feldspar and plagioclase feldspar are called granite.Rocks with no quartz and abundant plagioclase feldspar and pyroxene are called gabbro.Peridotite is denser than gabbro, is composed mainly of olivine and pyroxene.
35Extrusive Igneous Rocks 2Extrusive Igneous RocksExtrusive igneous rocks are those that cool from lava that has erupted at Earth’s surface.These rocks may have the same compositions as intrusive igneous rocks, but they always will have different textures.Composition of the surrounding rock material will also affect the extrusive magma.
36Extrusive Igneous Rock Composition Igneous Rocks2Extrusive Igneous Rock CompositionA magma rich in silica (SiO2) forms rhyolite if it cools rapidly.Similarly, gabbro’s fine-grained volcanic counterpart is basalt, which is a common rock in Earth’s oceanic crust.
37Extrusive Igneous Rock Composition Igneous Rocks2Extrusive Igneous Rock Composition
38Extrusive Igneous Rock Textures Igneous Rocks2Extrusive Igneous Rock TexturesIf cooling starts off slowly below the surface with large crystals, but then finishes at a faster rate to form small or no crystals, the extrusive rock is called porphyry.
39Igneous Rocks2Effect of GasesA texture called vesicular forms near the top surface of a flow where gases escape.
40Section Check2Question 1What might you expect to find if you examined a rock under a microscope?AnswerA rock is a naturally formed consolidated mixture containing minerals, rock fragments, or volcanic glass.
41Section Check2Question 2Igneous rocks form from molten rock material called _______.A. basaltB. silicaC. magmaD. granite
42Section Check2AnswerThe answer is C. There are two types of igneous rocks; intrusive and extrusive.
43Question 3 2 Extrusive igneous rocks form when _______ cools. A. lava Section Check2Question 3Extrusive igneous rocks form when _______ cools.A. lavaB. magmaC. waterD. volcanic glass
44Section Check2AnswerThe answer is B. When magma reaches Earth’s surface it is called lava.
45Rocks From Surface Materials Sedimentary Rocks3Rocks From Surface MaterialsRock is a consolidated mixture of minerals. Some of these minerals could be in bits and pieces of other rocks. Such small bits and pieces are called clasts.Rocks inside Earth are protected from surface conditions.Rock exposed at the surface is attacked by the weather.
46Transportation and Deposition Sedimentary Rocks3Transportation and DepositionMechanical weathering processes break into smaller clasts.When clasts are transported to new locations, they often become rounded before being deposited.When clasts are loose on Earth’s surface, they don’t fit together perfectly. The empty space in between the grains is called porosity.
47Transportation and Deposition Sedimentary Rocks3Transportation and DepositionWhen buried by more sediment deposited above them, clasts can be smashed together with such great force that they become compressed and stick together.This process is called compaction.
48Transportation and Deposition Sedimentary Rocks3Transportation and DepositionWater moving between clasts carries dissolved minerals that can act as cement. This process is called cementation.Most of the time both compaction and cementation work together to make sedimentary rock.
49Detrital Sedimentary Rock Sedimentary Rocks3Detrital Sedimentary RockDetritus is another name given to clasts.Clasts can come in many sizes.In order of decreasing size, clasts are known as gravel, sand, silt, or clay.
50Detrital Sedimentary Rock Sedimentary Rocks3Detrital Sedimentary RockGeologists have found that size works well as a clue to the kind of environment in which a rock formed.It takes more force, or energy, to lift or move gravel than it does to lift or move sand.
51Detrital Sedimentary Rock Sedimentary Rocks3Detrital Sedimentary RockDetrital sedimentary rock composition depends on sources to rock material that were eroded, transported, and eventually deposited.
52Detrital Sedimentary Rock Sedimentary Rocks3Detrital Sedimentary RockSome minerals tend to be more common in detrital sediments because they are harder or more resistant to being dissolved.Geologists examine sedimentary rock compositions and try to reconstruct what happened to form them.The general rock name is determined by the clast size.
53Detrital Sedimentary Rock Sedimentary Rocks3Detrital Sedimentary RockClast size also provides clues to help determine the deposition environment of the sediment that formed the detrital rock.
54Chemical Sedimentary Rocks Precipitation 3Chemical Sedimentary RocksPrecipitationIf water receives more dissolved materials than it can hold in solution, then the excess must precipitate out as microscopic crystals.EvaporationThe other option is for some water to evaporate.This leaves an oversupply of dissolved matter and again crystals.
55Biochemical Sedimentary Rocks 3Biochemical Sedimentary RocksIf sedimentary rocks contain the remains of living organisms they are called biochemical sedimentary rocks.Limestone is composed, of the remains of marine organisms that had hard parts made of calcium carbonate.Coal is sedimentary rock composed almost entirely of the carbon that remains after plant material is compressed underground.
56Biochemical Sedimentary Rocks 3Biochemical Sedimentary RocksCoal goes through a series of changes as it forms from peat.Each stage of compaction drives out more impurities and leaves behind a more concentrated form of carbon.
57Question 1 3 Small bits and pieces of rock are called _______. Section Check3Question 1Small bits and pieces of rock are called _______.A. clastsB. fragmentsC. pebblesD. pieces
58Section Check3AnswerThe answer is A. The word clast is from the Greek klastos which means “broken.”
59Question 2 3 Which is NOT a type of clast? A. clay B. gravel Section Check3Question 2Which is NOT a type of clast?A. clayB. gravelC. sedimentD. silt
60Section Check3AnswerThe answer is C. The four types of clasts are gravel, sand, silt, and clay. Sediment can contain any of these types of clasts.
61Section Check3Question 3_______ is a type of biochemical sedimentary rock that humans use to make electricity.A. CoalB. LimestoneC. GypsumD. Quartz
62Answer 3 The answer is A. Coal is composed almost entirely of carbon. Section Check3AnswerThe answer is A. Coal is composed almost entirely of carbon.
63Metamorphic Rocks and the Rock Cycle 4Metamorphic RocksMetamorphic rocks, have been changed by some combination of thermal energy, pressure, and chemical activity.Any igneous, sedimentary, or metamorphic rock is subject to change through metamorphism.
64Metamorphic Rock Composition Changing Minerals Metamorphic Rocks and the Rock Cycle4Metamorphic Rock CompositionChanging MineralsClay minerals tend to form micas with increasing metamorphic conditions.Some new minerals form by dehydration at higher temperature and pressure.
65Metamorphic Rocks and the Rock Cycle 4Changing MineralsDeep burial or regional movements of large parts of Earth’s crust and uppermost mantle cause regional metamorphism.Local contact of any preexisting rock with magma is called contact metamorphism.
66Metamorphic Rocks and the Rock Cycle 4Changing MineralsFoliated textures in metamorphic rocks have lots of layers or bands.Nonfoliated metamorphic textures include rocks whose grains are in more random orientations.
67Metamorphic Rocks and the Rock Cycle 4Foliated RocksThe most common sedimentary rocks in Earth’s crust are mudrocks.These rocks contain abundant clay minerals.
68Metamorphic Rocks and the Rock Cycle 4Foliated RocksNonfoliated metamorphic rocks tend to have random crystal orientation and uniform grain size.Mineral grains tend to grow as the grade of metamorphism increases.
69Metamorphic Rock Classification Metamorphic Rocks and the Rock Cycle4Metamorphic Rock ClassificationMuch like other rock types, metamorphic rocks can be classified based on texture and composition.
70Metamorphic Rock Classification Metamorphic Rocks and the Rock Cycle4Metamorphic Rock ClassificationMineral composition provides clues about the original rock type before metamorphism, and indicates to what degree a rock had been metamorphosed.
71Metamorphic Rocks and the Rock Cycle 4The Rock CycleProcesses of the rock cycle include any chemical and physical conditions that continuously form and change rocks.
72Question 1 4 Which is NOT an agent of metamorphism? Section Check4Question 1Which is NOT an agent of metamorphism?A. chemical activityB. pressureC. thermal energyD. wind
73Section Check4AnswerThe answer is D. Wind is responsible for erosion on some rocks but it does not help form them.
75Section Check4AnswerFoliated textures in metamorphic rocks have lots of layers or bands in them.
76Question 3 Answer 4 Is there a beginning and end to the rock cycle? Section Check4Question 3Is there a beginning and end to the rock cycle?AnswerNo, the rock cycle is a continual process in which rocks change from one form to another.
77HelpTo advance to the next item or next page click on any of the following keys: mouse, space bar, enter, down or forward arrow.Click on this icon to return to the table of contents.Click on this icon to return to the previous slide.Click on this icon to move to the next slide.Click on this icon to open the resources file.Click on this icon to go to the end of the presentation.