What Is a Mineral?

1. What Is a Mineral?

2. Terms to Know As we go through, write down the definitions of the words. • Inorganic • Physical Properties • Chemical Composition • Crystalline

3. Minerals Minerals are natural, inorganic solids that have a characteristic chemical composition, and orderly structure, and a characteristic set of physical properties

4. IS IT A MINERAL?4 BASIC QUESTIONS TO HELP YOU FIGURE IT OUT… Open your Earth Science book to page 103 What is the 1st way to determine whether or not a substance is a mineral or not?

5. 1. Is the substance organic? Minerals are inorganic which means they are not made up of living things or the remains of living things What is the second way to find out if the substance is a mineral?

6. 2. Does the substance occur naturally? Minerals form and exist in nature. Things that are made (manufactured) are NOT minerals What is the third way to find out if the substance is a mineral?

7. 3. Is the substance solid in crystalline form? Minerals have a regular, repeating structure which is referred to as a “crystalline” structure What is the fourth way to find out if the substance is a mineral?

8. 4. Does the substance have a consistent chemical composition? Minerals have a consistent chemical composition, which means that the chemicals that make up the substance are the same all the way through.

9. Two Main Groups of Minerals • Silicate • Non-Silicate

10. Silicates • Made up of a combination of silicon and oxygen (plus one or more additional elements • Make up about 96% of Earth’s crust • Includes Feldspars, Quartz and Ferromagnesian minerals such as olivines, pyroxenes, amphiboles, and biotite Quartz Pyroxene Olivine

11. Non-Silicates Non-Silicates do not contain compounds of silicon and oxygen and make up about 4% of Earth’s crust Includes 6 major groups: carbonates, halides, native elements, oxides, sulfates and sulfides

12. 7 Physical Properties of Minerals • Color • Streak – the color of the mineral in powder form • Luster – how it reflects light • Cleavage and fracture – how the mineral splits along weak areas • Hardness – the ability to resist scratching (measured using Moh’s Hardness Scale) • Crystal shape • Density – how closely its molecules are packed together

13. Rocks and the Rock Cycle

14. Let’s Rock! Rocks can be a mixture of both solid organic matter and minerals There are 3 major types of rocks: 1. Igneous 2. Sedimentary 3. Metamorphic

15. Igneous Rock Igneous rocks form when magma, or molten rock, cools and hardens

16. Sedimentary Rock Sediment is rocks, minerals, and organic matter that have been brokendown into smaller fragments through erosion Sedimentary rock is composed of sediment that has been compressed or cemented together and hardened

17. Metamorphic Rock Metamorphic rock is rock that is formed due to pressure and heat (but NOT melting!!!)

18. The Rock Cycle Rocks are constantly going through the “rock cycle” which changes one type of rock into another over time.

19. The Rock Cycle

20. Intrusive Igneous Rocks Intrusions form when magma “intrudes” or enters into another rock mass and then cools

21. Sedimentary Rocks Sedimentary rock is formed in two main processes: 1. Compaction – sediment is squeezed and the size of the space between sediment grains is reduced by weight and pressure of layers on top of the sediment 2. Cementation – sediments are “glued” together by minerals that are deposited by water as it travels through the sediment

22. Depositional Environment of Sedimentary Rocks DepositionalEnvironment just means what it was like in the area when the sediment settled or deposited itself there. Each depositional environment has different characteristics that create specific structures in the sedimentary rock…this tells us a lot about what it was like there when that layer of rock happened

23. Depositional Environment ofSedimentary Rocks Stratification is the layering of sedimentary rock The kind of environment in that produces stratification shows that the conditions were in a state of change….maybe one area that was once part of a sea or ocean became a desert and then eventually changed into grasslands

24. Depositional Environment of Sedimentary Rocks Cross beds are generally formed in sand dunes or river beds Cross beds are characterized by slanting layers

25. Metamorphic Rock The process by which heat or pressure or change one type of rock into another is called metamorphism

26. Types of Metamorphic Rock Foliated Rock – metamorphic rock texture in which minerals are arranged in planes or bands called foliation Non-Foliated – metamorphic rock that does not have bands or planes

27. The Rock Record

28. The Rock Record Before James Hutton’s research on the age of the Earth, people thought the Earth was about 6,000 years old. During the 18th Century, Hutton theories caused geologists to estimate the Earth’s age really to be around 4.6 BILLION years old!

29. Uniformitarianism Uniformitarianism is James Hutton’s theory that current geologic processes, such as volcanism and erosion, are the same processes that were at work in the past….Makes sense, right??

30. Relative Age • Layers of rock called strata show the sequence of events that took place in the past. • Relative age of a particular rock layer can be determined by looking at other rocks and rock layers in relation to the rock • Relative age shows that one layer of rock is older or younger than another but does NOT show the rock’s age in years.

31. Law of Superposition The law that states that a sedimentary rock layer is older than the layers above it and younger than the layers below it if the layers are not disturbed

32. Let’s Test the Law of Superposition! We will need sand and modeling clay and a small clear container. • Put a layer of modeling clay into the bottom of the container • Put a layer of sand into the same container • Repeat steps one and two Out of all your layers, which one has been there the longest? Which one is the newest?

33. Principle of Original Horizontality The Principle of Original Horizontality states that sedimentary rocks that are left undisturbed will remain in horizontal layers. Due to this principle, scientists can assume that sedimentary rock layers that are NOT horizontal have been tilted or deformed by movements in the Earth

34. Sedimentary Rock Layer Structures Graded Bedding – the arrangement of layers in which coarse, heavy particles are located in the bottom layers Cross-beds - made when sandy sediment forms curved beds at an angle to the horizontal bedding Ripple marks – small waves that form on the surface of sand because of the action of water or wind

35. Unconformities Unconformities are a break in the geologic record created when rock layers are eroded or when sediment is not deposited for a long period of time

36. Crosscutting Relationships The Law of Crosscutting Relationships states that a fault or body of rock is younger than any other body of rock it cuts through

37. Absolute Age The actual numerical age of an object or by an absolute dating process

38. Absolute Dating Methods • Rates of Erosion - how fast erosion occurs • Rates of Deposition - how fast sediment is deposited • Varve Count - annual layers of sediment • Radiometric Dating – comparing the relative percentages of radioactive parent isotopes and a stable daughter isotope

39. Half-Life The time required for half of a sample of radioactive parent isotope to break down by radioactive decay to form a daughter isotope

40. Carbon Dating Most objects contain carbon and can be dated according to how fast the 14carbon has combined with oxygen to break down into radioactive carbon dioxide (CO2-)

41. Fossil Record The study of fossils is called paleontology Fossils are the trace or remains of an organism that lived long ago, most commonly preserved in sedimentary rock

42. How fossils form • Mummification • Amber • Tar Seeps • Freezing • Petrification • Imprints • Molds and casts • Coprolites • Gastroliths

43. 1. Mummification Normally mummification happens in dry areas where bacteria cannot live. This can happen naturally, or as in the case of the ancient Egyptians, through burial processes by people Pompeii http://www.history.com/topics/pompeii/videos#deconstructing-history-pompeii How to make a mummy http://www.history.com/videos/how-to-make-a-mummy#how-to-make-a-mummy

44. 2. Amber Amber is just hardened tree sap. If an organism is caught in the amber it can be fossilized within

45. 3. Tar Seeps • Tar seeps happen when petroleum rises to the Earth’s surface and seeps out. • Since the tar is often covered by water many animals get trapped in the sticky tar

46. 4. Freezing • Since bacteria cannot survive freezing, organisms that have frozen do not decay. Iceman mummy clip http://dsc.discovery.com/tv-shows/other-shows/videos/assignment-discovery-shorts-ice-mummy.htm Girl with frozen mammoth

47. 5. Petrification • This happens when inorganic (non-living) minerals slowing replace organic (living material) • This can produce a perfect replica of the original object

48. 6. Imprints • When the original object decays it sometimes leaves behind it’s shape in a carbon-rich film

49. 7. Molds and Casts Shells and other organisms have hollow insides and create a mold or cast of their shape when buried in mud or sediment

50. 8. Coprolites Petrified poo! Scientists can study these to see what kind of feeding habits ancient creatures had