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Rocks and Minerals. Minerals the building blocks of rocks Mineral Characteristics natural inorganic solid definite composition crystal structure.

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Presentation on theme: "Rocks and Minerals. Minerals the building blocks of rocks Mineral Characteristics natural inorganic solid definite composition crystal structure."— Presentation transcript:

1 Rocks and Minerals

2 Minerals the building blocks of rocks Mineral Characteristics natural inorganic solid definite composition crystal structure

3 Mineral Formation 4 major processes by which minerals form: 1. Crystallization from magma- cooling magma causes minerals to crystallize

4 2. Precipitation Minerals dissolve out of evaporated water; precipitated

5 3. Pressure and Temperature Change in pressure and temperature cause an existing mineral to recrystallize while still solid Muscovite Talc

6 4. Hydrothermal Solutions A hot mixtures of water with substances dissolved in them. When they come in contact with existing minerals- a chemical reaction occurs forming a new mineral Bornite

7 Mineral Composition Minerals are grouped or classified based on their composition. There are 6 groups 1. Carbonates - contain carbon, oxygen, and one ore more metallic element

8 2. Silicates -formed from silicon and oxygen -elements combined to form a silicon tetrahedron, 1 silicon atom and 4 oxygen atoms -formed from cooling magma -either near the surface (few crystals) or deep below surface (larger crystals)

9 3. Oxides - Minerals that contain oxygen and one or more other element(s )

10 4. Sulfates and Sulfides - Minerals containing sulfur Gypsum Pyrite

11 5. Halides - minerals containing halogen ions plus one or more other elements Halite

12 6. Native Elements Minerals that exist in a relatively pure form gold, silver, copper Gold crystal structure

13 Mineral Properties Mineral PROPERTIES are used to identify minerals based on specific characteristics Luster Streak Color Specific Gravity Cleavage & Fracture Hardness Magnetism Fluoresence

14 Streak color of a mineral in its powder form Color often not a good property for Iding

15 Luster how light is reflected from the surface of a mineral

16 Cleavage- tendency to break along flat, even surfaces (mica) Fracture- uneven breakage (quartz)

17 Specific Gravity- ratio of a mineral’s density to the density of water Specific Gravity = mass (g) of dry sample mass lost in water Specific Gravity is a ratio…so Specific Gravity has no units

18 Hardness- measure of resistance of a mineral being scratched

19 Magnetism Magnetite Fluorescence Double Refraction Calcite Smell Sulfur

20 Rocks and The Rock Cycle

21 Rocks- any solid mass of mineral or mineral-like matter that occurs naturally as part of our planet There are 3 major type or families or rock: –Igneous rocks –Sedimentary rocks –Metamorphic rocks

22 Igneous Rocks Magma- molten material underground Lava- magma that reaches the surface Igneous rocks are formed from magma that has cooled and hardened either beneath the surface or from a volcanic eruption

23 2 Ways to Form Igneous Rock Intrusive Igneous Rocks- form when magma hardens beneath Earth’s surface Magma intrudes into existing rocks Extrusive Igneous Rocks- form when lava hardens on the surface of the Earth Extruded onto the surface granite rhyolite

24 Magma contains some gases, including water vapor- this make it less dense, so it rises As magma rises, it cools and forms crystals The longer the cooling time the larger the crystals

25 Classification of Igneous Rocks Igneous rocks are classified by texture and composition Texture refers to the appearance of an igneous rock (size, shape, arrangement of crystals) Composition refers to the proportions of light and dark minerals in the rock

26 Coarse- grained Texture- form as a result of slow cooling, ions can move = large crystal size Fine-grained Texture- form as a result of quick cooling time, ions lose motion= small crystal size Glassy Texture- form from lava that cools rapidly, ions don’t have time to arrange = glassy texture Porphyritic Texture- rocks with different size minerals that form from varying cooling rates

27 Felsic Composition- contain mainly quartz and feldspar, some with biotite mica and amphibole. Make up major rocks of continental crust Mafic Composition- contain mainly dark colored minerals and feldspar, along with Mg and Fe. Darker and denser than granitic composition

28 Classification of Major Igneous Rocks Texture is crossed with composition to classify igneous rocks. For example, granite has a coarse texture due to slow cooling and larger crystals, and a light color from the light colored quartz and feldspar minerals used to form it.

29 Sedimentary Rocks- formed from compacted and cemented sediments Weathering physically and chemically breaks rocks into small pieces called sediments Sediments are moved by wind, water, ice, and gravity Eventually, they are dropped and form layers that are cemented together

30 Weathering, Erosion, and Deposition Weathering breaks rocks down Erosion involves weather and the removal of rock Deposition is the dropping of sediments Sediments are deposited according to size

31 Compaction and Cementation Compaction is the process that squeezes the water out of the sediments. It is caused by the weight of the sediments. Cementation takes place when dissolved minerals are deposited in the tiny spaces among the sediments. Cementing holds the sediments together.

32 Classification of Sedimentary Rocks Clastic Sedimentary Rocks are formed from weathered bits of rocks and minerals Organic Sedimentary Rocks are formed from living materials Chemical Sedimentary Rocks are formed when dissolved minerals precipitate from water solution rock salt limestone

33 Sedimentary rocks hold many clues to the Earth’s history Layers of sediments are records of geologic events on Earth Fossils are unique to sedimentary rocks

34 Sedimentary rocks drop according to size; larger particles fall first followed by smaller particles

35 Metamorphic Rocks- form when existing rocks undergo change through heat and pressure Metamorphism means to change Most metamorphic changes occur at high temperatures and pressure These occur deep below the Earth’s surface and extend into the mantle

36 Forms of Metamorphism Contact Metamorphism- forms when magma intrudes into existing rock Changes in rocks are minor Regional Metamorphism- formed during mountain building process that occur over a large area Major changes to rocks

37 Contact metamorphismRegional metamorphism

38 Agents of Metamorphism Heat- causes existing minerals to recrystallize or new minerals to form Pressure- causes the spaces between mineral grains to close= more compact rock= greater density

39 Classification of Metamorphic Rocks - based on texture and composition Foliated Metamorphic Rocks- form when minerals recrystallize at right angles to the direction of force Causes a layered or banded appearance Nonfoliated Metamorphic Rocks- no banded texture Most contain only one mineral

40 FoliatedNonFoliated slate gneiss schist marble

41 The Rock Cycle

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43 Thinking about relationships among the major rock groups

44 Major Rock Groups Igneous –Formed from a melt (molten rock) –Plutonic (intrusive):slow cooling and crystallization –Volcanic (extrusion): quick cooling at the surface Sedimentary –Formed at the Earth’s surface –Clastic (Mineral Fragments or grains, clays) –Chemical (crystalline chemical/biochemical precipitates) –Organic (made from living material: shells, plants) Metamorphic –Changed by pressure, heat and fluids.

45 Fig. 2.9 MAGMA

46 46 MAGMA Crystallization IGNEOUS

47 47 MAGMA IGNEOUS Intrusive/Plutonic Crystallization

48 48 MAGMA Extrusive/Volcanic IGNEOUS Intrusive/Plutonic Crystallization

49 49 MAGMAUplift Crystallization Weathering Extrusive/Volcanic IGNEOUS Intrusive/Plutonic

50 50 MAGMA SEDIMENT Uplift Crystallization Weathering SEDIMENT Extrusive/Volcanic IGNEOUS Intrusive/Plutonic

51 51 MAGMA SEDIMENT SEDIMENTARY Uplift Crystallization Weathering Erosion Transport Deposition Extrusive/Volcanic IGNEOUS Intrusive/Plutonic

52 52 MAGMA SEDIMENT SEDIMENTARY Uplift Crystallization Weathering Erosion Transport Deposition Extrusive/Volcanic IGNEOUS Intrusive/Plutonic

53 53 MAGMA SEDIMENT SEDIMENTARY METAMORPHIC Uplift Burial Increased P&T Crystallization Weathering Erosion Transport Deposition Extrusive/Volcanic IGNEOUS Intrusive/Plutonic

54 54 MAGMA SEDIMENT SEDIMENTARY METAMORPHIC Uplift Burial Increased P&T Melting Crystallization Weathering Erosion Transport Deposition Add the Shortcuts Extrusive/Volcanic IGNEOUS Intrusive/Plutonic

55 55 MAGMA SEDIMENT SEDIMENTARY METAMORPHIC Uplift Burial Increased P&T Melting Crystallization Weathering Erosion Transport Deposition Extrusive/Volcanic IGNEOUS Intrusive/Plutonic

56 56 MAGMA SEDIMENT SEDIMENTARY METAMORPHIC Uplift Burial Increased P&T Melting Crystallization Weathering Erosion Transport Deposition Extrusive/Volcanic IGNEOUS Intrusive/Plutonic

57 The rock cycle demonstrates the relationships among the three major rock groups It is powered by the interior heat of the Earth As well as earth’s momentum and… The energy from the sun It involves processes on the Earth’s surface as well as the Earth’s interior It connects the “hydrologic cycle” with the “tectonic cycle”. In Conclusion…

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59 ROCK CYCLE The surface of the Earth is made of rockThe surface of the Earth is made of rock ROCK is a collection of one or more minerals, mixed together into a solid substanceROCK is a collection of one or more minerals, mixed together into a solid substance

60 Rock Cycle The Series of processes in which rock forms and changes from one type to another by geological processes.The Series of processes in which rock forms and changes from one type to another by geological processes.

61 PROPERTIES OF ROCKS BOWEN’S REACTION SERIES: The pattern that shows how minerals form crystals when they cool based on their chemical make-up and melting pointBOWEN’S REACTION SERIES: The pattern that shows how minerals form crystals when they cool based on their chemical make-up and melting point

62 The Rock Cycle -Melting & Intrusion -Solidification of melt -Mountain Building -Uplift & Exposure -Weathering -Erosion & Transport -Deposition & Burial -Metamorphism -Melting & Intrusion Fig 4.9

63 The Rock Cycle Fig 4.9 Convergent Plate Boundary -Subducting slab -Mantle melting -Bouyant rise of melt

64 The Rock Cycle Fig 4.9 Convergent Plate Boundary - Solidification of melt - Volcanic activity Intrusive rocks Extrusive rocks


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