GEOLOGY 306 Laboratory Instructor: TERRY J. BOROUGHS NAME: Section: Pre-Lab and Introduction to Physical Properties of Rocks Assignment for: Common Rocks (Chapter 2) For this assignment, you will require: a streak plate, glass plate, magnet, dilute hydrochloric (HCl) acid, microscope, and various mineral samples (all provided by instructor). Objectives for chapter 2: you should be able to recognize, name, and describe individual minerals within rocks; be able to examine a rock and determine if it is an igneous, sedimentary, or metamorphic rock; list and define the terms used to describe the textures of igneous, sedimentary, and metamorphic rocks; use a classification key to identify a rock; recognize and name some of the common rocks by sight. THE FOLLOWING QUESTIONS REFER TO CHAPTER 2 IN YOUR MANUAL (Read the questions from your manual and place your answers in the following spaces provided.) 1. Use Figures 2.4. 2.5, 2.7, 2.9, 2.10, 2.11, 2.13, 2.19, 2.20, 2.21 (8 th edition) for this question. Of igneous, sedimentary, and metamorphic rocks which two of the three basic rock types appear to made mostly of inter-grown (interlocking) crystals? 2. Which one of the two rock types you listed in question 1 have mineral grains or crystals aligned or arranged so that they point in the same direction in a linear, line-like manner? 3. Which one of the two rock types you listed in question 1 have the mineral crystals in most of the rocks arranged in a dense interlocking mass with no alignment? 4. Of the three rock types (igneous, sedimentary, or metamorphic) rocks are most often contain haphazardly arranged pieces or fragments, rather than crystals? (Select the best answer) 5. The igneous rock illustrated in Figure 2.9 A (8 th edition) is made of large mineral crystals that are all about the same size. The rock formed from magma that cooled (slowly, rapidly) and (inside, on/near the surface of) the Earth. (Select the best answers). 6. The rock shown in Figure 2.9 C (8 th edition) is made of mineral crystals that are all small and not identifiable without a microscope. The rock formed from magma that cooled (slowly, rapidly) and (inside, on/near the surface of) the Earth. (Select the best answers). 7. The igneous rock in Figure 2.9 G (8 th edition) has a porphyritic texture. The large crystals are called and the surrounding smaller crystals are called 10. Estimate the percentage of dark minerals contained in the igneous rock in Figure 2.11 D (8 th edition) (You may find the color index at the at the bottom of Figure 2.10 (8 th edition), Igneous & Rock Identification Key, helpful) The rock s color is (light, medium, dark, or very dark). Select the best answer. 1
1. Identify the three different types of rocks involved in the rock cycle: Igneous Rocks: 2. Which of these pictures formed by slow cooling (formed underground)? Select the appropriate letter(s). A B 3. Which of the previous pictures (A & B) formed by rapid cooling (formed on the surface)? Select the 4. Which of the previous pictures (A & B) formed a pegmatitic texture with crystals larger than an inch in size? Select the 5. Which of the previous pictures (A & B) produced a glassy texture? Select the 6. Which of these pictures formed by two or more stages of cooling, producing crystals of different sizes? Select the C D 7. Which of the previous pictures (C & D) represents a phaneritic texture produced by slow, uniform cooling? Select the 8. Which of the previous pictures (C & D) represents a porphyritic texture with phenocrysts surrounded by smaller grained matrix? Select the Are the light or dark crystals the Phenocrysts? 2
9. Which of these pictures contains vesicles that formed as the magma cooled around and preserved gas bubbles? Select the appropriate letter(s). E F 10. Which of the previous pictures (E & F) represents a Pyroclastic or Fragmental texture? Select the 11. Which of the previous pictures (E & F) depicts a dark and mafic appearance? Select the 12. Which of the previous pictures (E & F) depicts a light and felsic appearance? Select the 13. Which of these pictures depicts a light, felsic composition? Select the G D 14. Which of the previous pictures (G & D) depicts an intermediate composition? Select the 3
15. Which of these pictures (A & H) produced a glassy texture? Select the appropriate letter. A H 16. Which of the previous pictures (A & H) produced a Frothy (glassy and vesicular) texture? Select the Sedimentary Rocks: 17. Which of these pictures depicting Clastic and/or detrital sedimentary rocks has large rounded grains? Select the A B C 18. Which of the previous pictures (A, B, & C) which depict Clastic or detrital sedimentary rocks has large angular grains? Select the 4
19. Which of the previous pictures (A, B, & C) which depict Clastic or detrital sedimentary rocks has medium and uniform, well sorted grains? Select the 20. Depending upon the amount of travel sedimentary grains accomplish prior to deposition, the grains will tumble in rivers, etc. and become more rounded and uniform with time. Which of the previous pictures (A, B, & C) depicts sediments that have not travelled far from their source? Select the 21. Which of the previous pictures (A, B, & C) depicts sediments that have travelled the furthest from their source? Select the 22. These pictures depict Chemical sedimentary rocks that are crystalline or microcrystalline. Which one of these rocks contain visible crystals? Select the D 23. Which of the previous pictures (D & E) contain tiny, microscopic crystals that are not visible? Select the E 24. These pictures represent biological or organic rocks (can also be Bioclastic). Which of these rocks contain intact or whole fossils? Select the F G 5
25. Which of these rocks (F & G) contain fossil fragments? Select the Metamorphic Rocks: These pictures of foliated metamorphic rocks depict an increase in metamorphism to the right. -> -> -> 26. Which of these Pictures exhibit Foliation? Select the A B 27. Which of the previous Pictures (A & B) do NOT exhibit Foliation? Select the appropriate letter(s). 28. Which of the previous Pictures (A & B) exhibit color banding or color streaking? Select the appropriate letter(s). 29. Which of the following Pictures (C & D) exhibit Porphyroblasts, which are large crystals that grow preferentially during metamorphism? Select the 6
C 30. Of pictures C and D, which picture exhibits a more uniform non-foliated appearance? Select the D 31. Of Pictures C and D which picture exhibits larger crystals? Select the appropriate letter 32. Of Pictures B and D, which pictures exhibits a more granular appearance? Select the 33. What are the agents of Metamorphism? 34. Use Figure 2.16 (8 th edition) to name the environment(s) where, in the past, the sediment for the following sedimentary rocks may have been deposited. Use the following table: Rock type: Original Sediment Environment(s) Rock Gypsum: Bituminous Coal Fossilferous Limestone: Travertine Quartz Sandstone: (precipitated Gypsum) (carbon) (coral) (precipitated calcite) (Wind-faceted quartz particles) 35. What characteristic can be used to distinguish Conglomerate from Breccia? (In other words, how would you tell them apart?) 7
35. Figure 2.13 C (8 th edition) is the rock sandstone that formed from sand. Where on Earth do you find sand, the primary material of sandstone, being deposited today? List at least two environments. 36. Of the three basic rock types, which one is most likely to contain fossils? 37. From the rocks illustrated in Figure 2.19 A and C (8 th edition), the (slate, schist) resulted from more intensive heat and pressure. Select the best answer. 38. From the metamorphic rocks in Figure 2.19 B and D (8 th edition), the (phyllite, gneiss) shows the minerals separated into light and dark bands. Select the best answer. (The foliated-banded texture of the rock that you have selected often results from the most intensive heat and pressure during metamorphism) 39. What unique factor about the arrangement of mineral crystals that occurs in many metamorphic rocks? 40. Referring to Figure 2.23 A, B, & C (8 th edition) identify whether each outcrop is igneous, sedimentary, or metamorphic in origin. Outcrop A: Outcrop B: Outcrop C: THE END!! HAVE A GNEISS DAY! 8