Rocks, Minerals & the Rock Cycle

1. Rocks, Minerals & the Rock Cycle

2. Section 1 Minerals and Mineral Resources Chapter 16 Objectives • Definethe term mineral. • Explainthe difference between a metal and a nonmetal, and give two examples of each. • Describethree processes by which ore minerals form.

3. Mineral Resources • We depend on the use of mineral resources in almost every aspect of our daily life. • However, our dependence on minerals has not come without a price. • The current challenge is to obtain the minerals that an ever-increasing world population demands at minimalcost to the environment.

4. Mineral Consumption per Person (U.S.)

5. What Is a Mineral? • A mineral is a naturallyoccurring, usually inorganic solid that has a characteristic chemical composition, an orderly internal structure, and a characteristic set of physical properties. • Minerals are made up of atoms of a single element, or of compounds. A compound consists ofatoms of two or more elements chemically bonded together. • The atoms that make up minerals are arranged in regular, repeatinggeometricpatterns.

6. Section 1 Minerals and Mineral Resources Chapter 16 What Is a Mineral? • The arrangement of the atoms, along with the strength of the chemical bonds between them, determine the physical properties of minerals, • Some elements, called native elements, are considered minerals. These include the elements gold, silver, and copper. • Most minerals, however, are compounds. • The mineral quartz is made up of silica, which consists of one silicon atom and two oxygen atoms.

7. Section 1 Minerals and Mineral Resources Chapter 16 Ore Minerals • An ore mineral is a mineral that contains one or more elements of economic value. • During the mining process, gangue minerals, minerals with no commercial value, are extracted along with ore minerals. • Ore minerals, once separated from the gangue minerals, are refined using various methods to extract the valuable elements they contain. • For mining to be profitable, the price of the final product must be greater than the costs of extraction and refining.

8. Section 1 Minerals and Mineral Resources Chapter 16 Ore Minerals

9. Section 1 Minerals and Mineral Resources Chapter 16 Metallic Minerals • Ore minerals are either metallic or nonmetallic. • Metals have the following characteristics: • can conduct electricity • have shiny surfaces • are opaque • Many valuable metallic minerals are native elements, such as gold, silver, and copper. • Other important ore minerals are compounds of metallic minerals with nonmetallic elements.

10. Section 1 Minerals and Mineral Resources Chapter 16 Nonmetallic Minerals • Nonmetals have the following characteristics: • tend to be good insulators • may have shiny or dull surfaces • may allow light to pass through • Nonmetallic minerals can also be native elements or compounds.

11. Section 1 Minerals and Mineral Resources Chapter 16 How Do Ore Minerals Form? • Economically important ore deposits form in a variety of ways, both on and beneath Earth’s surface. • The types of mineral that form depend on the environment in which they form.

12. Section 1 Minerals and Mineral Resources Chapter 16 Mineral Environments

13. Section 1 Minerals and Mineral Resources Chapter 16 Hydrothermal Solutions • Hot, subsurface waters that contain dissolved minerals are called hydrothermal solutions. • Hydrothermal solutions dissolve minerals as they flow through cracks in rocks. • New minerals crystallize out of these solutions and then fill fractures to form ore deposits called veins. • Many economically valuable metallic ores form in this way.

14. Section 1 Minerals and Mineral Resources Chapter 16 Evaporites • When water in the seas or lakes evaporate, they leave behind deposits of salts called evaporites. • Evaporites form in arid regions where rates of evaporation are high. • Halite (rock salt) and gypsum are important evaporite minerals.

15. Section 1 Minerals and Mineral Resources Chapter 16 Mineral Resources and Their Uses • Certain metals are of major economic and industrial importance. • Some metals can be pounded or pressed into various shapes or stretched very thinly without breaking. Others conduct electricity well. • Often two or more metals are used to form alloys, which combine the most desirous properties of the metals used to make them.

16. Section 1 Minerals and Mineral Resources Chapter 16 Mineral Resources and Their Uses

17. Rocks And The Rock Cycle

18. Why Are Rocks Important To Us? Buildings Roads Bridges Concrete Extract minerals – like iron (Fe) to make steel Toothpaste Salt Sandpaper Decorations Jewelry

19. 1. Why is it important to have a basic understanding of the rock cycle? Rocks contain clues about the environment. Helps us understand the formation of the earth.

20. 2. Rock Any solid mass of minerals or mineral-like matter

21. 3. Do most rocks occur as one mineral or as a mixture of minerals? Mixture

22. 4. Some rocks are made of non-mineral material, can you name one? Coal

23. Coal - begins as layers of plant matter accumulate at the bottom of a body of water. For the process to continue the plant matter must be protected from biodegradation and oxidization, usually by mud or acidic water. This trapped atmospheric carbon in the ground in immense peatbogs that eventually were covered over and deeply buried by sediments under which they metamorphosed into coal. Over time, the chemical and physical properties of the plant remains (believed to mainly have been fern-like species antedating more modern plant and tree species) were changed by geological action to create a solid material. Coal, a fossil fuel, is the largest source of energy for the generation of electricity worldwide.

26. 5. Explain the rock cycle. A continuous process that causes rock to change from one form to another 2 1 3 5 4

28. The Rock Cycle • The Rock Cycle is a group of changes, this change does not necessarily have to be a chemical change. • Igneous rock can change into sedimentary rock or into metamorphic rock. • Sedimentary rock can change into metamorphic rock or into igneous rock. • Metamorphic rock can change into igneous or sedimentary rock. • Almost all of rock today that we have on earth is made up of all the same stuff as the rocks that dinosaurs and other ancient life forms walked, crawled, or swam over • While the stuff that rocks are made of has stayed the same, the rocks themselves, have not • Over time rocks are recycled into other rocks • Moving tectonic plates are responsible for destroying and forming many types of rocks

29. 6. List the 3 types of rocks Igneous Metamorphic Sedimentary

30. 7. Igneous Rocks • Igneous rock forms when magma cools and makes crystals. • Magma is a hot liquid made of melted minerals. When magma pours onto the earth’s surface it is called lava. The minerals can form crystals when they cool. • Igneous rock can form underground, where the magma cools slowly. Or, igneous rock can form above ground, where the magma cools quickly. • The crystals grow together and form one igneous rocks.

31. 8. What kind of igneous rocks form when molten lava cools and hardens? Extrusive Extrusive = forced out while molten through cracks in the earth's surface

32. 9. What is the Latin word that the word igneous comes from and what does it mean? ignis = fire

33. 10. Intrusive Igneous Rocks Form from magma below the earth’s surface

34. 11. Extrusive Igneous Rocks Formed by lava on the Earth’s surface

35. 12. What is the difference between magma and lava? Lava = molten rock flowing on the earth’s surface Magma = molten rock below the earth’s surface

36. 13. What are the 8 elements that make up magma? Silicon, oxygen, aluminum, iron, calcium, sodium, potassium, magnesium

37. Granite Rhyolite Look at the granite rock (A on age 71) and the rhyolite rock (B on page 71) 14. In what ways are the two rocks similar? Both are from melted rock Their composition is the same

38. Granite Rhyolite 15. In what ways are the two rocks different? Granite – coarse texture, made from magma Rhyolite – fine texture, made from lava

39. Granite Rhyolite 16. What causes the two rocks to be different? Granite – Slow cooling below the earth’s surface Rhyolite – Quick cooling on the earth’s surface

40. 17. Why do you think some rocks are heavier than others? Some are denser – less air space between particles

41. Which rock would have greater density? Pumice Granite

42. Classifying Rocks Rocks can be classified, or put into groups with similar characteristics, by looking at the rocks texture, mineral composition, and color.

43. 18. What is texture? The size, shape, and pattern of the rock’s grain Glassy (nice)

44. 19. Composition (what’s it made of?) The minerals that make up the different parts of a rock Examples:QuartzFeldsparMagnesiumIron

45. ADD Rock Color The apparent color of the rock, on the inside and the outside

46. Metamorphic rocks are rocks that have "morphed" into another kind of rock. These rocks were once igneous or sedimentary rocks. How do sedimentary and igneous rocks change? The rocks are under tons and tons of pressure, which fosters heat build up, and this causes them to change. If you exam metamorphic rock samples closely, you'll discover how flattened some of the grains in the rock are.

47. The Rock Divisions • Rock divisions occur in three major families based on how they formed: igneous, sedimentary, and metamorphic. • Each group contains a collection of rock types that differ from each other on the basis of the size, shape, and arrangement of mineral grains. • Just remember 3 types of rocks=3 divisions. (igneous, sedimentary, and metamorphic)

48. Classifying Rocks • When classifying a rock sample geologists observe the rock’s color and texture and determine its mineral composition. • Texture: the size, shape, and pattern of the rock’s grain. • Color: the apparent color of the rock, on the inside and the outside. • Mineral composition: The minerals that make up the different parts of a rock.

49. Often, the grains in a rock are large and easy to see. Such rocks are said to be coarse-grained. In other rocks, the grains are so small that they can only be seen with a microscope. These rocks are said to be fine-grained. Notice the difference in texture between the fine-grained slate and the coarse-grained diorite to the right. Texture: Grain Size

50. Texture: Grain Shape • The grains in a rock vary widely in shape • Some grains look like tiny particles of fine sand • Others look like small seeds or exploding stars • In some rocks, such as granite, the grain results from the shapes of the crystals that form the rock • In other rocks, the grain shape results from fragments of other rock • These fragments can be smooth and rounded, like the fragments in conglomerate, or they can be jagged, like the fragments in breccia • You can compare conglomerate and breccia one the next slide