The Study of Minerals (Chapter 1)

Transcription

1 GEOLOGY 306 Laboratory Instructor: TERRY J. BOROUGHS NAME: The Study of Minerals (Chapter 1) For this assignment you will require: a streak plate, glass plate, magnet, dilute hydrochloric (HCl) acid, microscope, contact goniometer, and various mineral samples (all provided by instructor). Objectives for chapter 1: you should be able to recognize and describe the physical properties of minerals; use a mineral identification key to name minerals; identify several minerals by sight; and list the uses of several minerals that are mined. THE FOLLOWING QUESTIONS REFER TO CHAPTER 1 IN YOUR MANUAL (Read the questions from your manual and place your answers in the following spaces provided.) 1. Use the samples provided especially for this question, labeled 1A through 1E, and identify which ones exhibit metallic or non-metallic luster by placing their labels in the appropriate category. Metallic: Nonmetallic-glassy: 2. Use the samples provided especially for this question, labeled 2A through 2E, and identify which ones are transparent or opaque by placing their labels in the appropriate category. Transparent: Opaque 3. Using figure 1.3 A and Smart Figure 1.4 (8 th edition) several varieties of quartz and/or fluorite exhibit a variety of colors. What is the reason for the variety of colors that these samples exhibit even though they represent the same mineral? 4. Use the samples provided especially for this question, labeled 4A through 4E. Identify by letter, the samples that are the same mineral, the remaining samples will represent a variety of different minerals. 5. Use the samples provided especially for this question, labeled 5A through 5E and identify the color of the specimen (sample) vs. the color of the streak when scraped across a porcelain plate. Be as detailed as possible when describing these colors. Sometimes subtle differences will help distinguish between similar minerals. Color of Specimen A. B. C. D. E. Color of Streak 6. Use the samples provided especially for this question, labeled 6A through 6E. Place them in order of hardness from softest to hardest, using their labels. Softest Hardest Instructor: Ms. Terry J. Boroughs 1

2 7. In figure 1.8 (8 th edition) two samples of the mineral hematite are shown with their corresponding streaks. A. Do the samples exhibit the same (or similar) color or not? B. Are their streaks the same (similar) or different? A B 8. Use the geologic definition (5 criteria) of a mineral to determine which of the items listed below are minerals and which are not minerals. Quartz (Mineral or Not): Cubic Zirconia (Mineral or Not): Motor oil (Mineral or Not): Hydrogen (Mineral or Not): Emerald (Mineral or Not): Rain water (Mineral or Not): Vitamin D (Mineral or Not): Halite (Mineral or Not): Rock candy (Mineral or Not): Obsidian (Mineral or Not): 9. The mineral shown in Figure 1.10 A (8 th edition) has a well-developed crystal form with six faces that intersect at about 120 degrees and come to a point. Two varieties of the same mineral are shown in Figure 1.26 (8 th edition), why do they not exhibit crystal form? 10. Select one of the photographed minerals other than Figure 1.10 A (8 th edition) that exhibits crystal form (not cleavage!) and describe its shape. Figure: Crystal Shape: 11. Use the goniometer and samples provided especially for this question, labeled 11A through 11C. Measure the angle between adjacent faces on the quartz crystals for each sample. A. Are the angles similar for the quartz samples or do they vary from one sample to another? B. Does the size of the sample influence the angle? A. B. 12. See question # 1, page 10 (8 th edition) in manual. 13. See question # 2, page 10 (8 th edition) in manual. A. Surfaces or (sides) of cleavage B. Directions of cleavage C. Cleavage angle 14. Use the sample provided especially for this question, labeled 14. Identify the cleavage of the sample. Directions of cleavage: Cleavage angle (at 90 or not at 90 ): 15. Use the samples provided especially for this question, labeled 15A through 15C. Determine which sample has the highest Specific Gravity by hefting the sample (within its container) in your hand and determining which one seems heaviest for its size. Sample has the highest specific gravity. 16. Use the samples provided especially for this question, labeled 16A through 16F. Don t taste the samples, once you have identified the other physical properties, the one remaining will have a distinctive taste. Match the letter with the corresponding physical property and identify any specifics, i.e. the feel is soapy vs. greasy, etc. Magnetism: Striations: Feel: Reacts with Acid: Taste: Tenacity: Instructor: Ms. Terry J. Boroughs 2

3 17. Use the mineral identification key figure 1.24 (8 th edition) to determine the name of the mineral with the following properties: non-metallic luster, light-colored, softer than a fingernail, produces small thin plates or sheets when scratched by a fingernail, white color, and a soapy feel. 18. Questions 18 through 20 refers to Figure 1.23 (8 th edition) in your manual. Instead, please answer the following questions concerning samples A through X using the following terminology and information: OBJECTIVE: To be able to identify minerals based upon their physical properties and to be able to determine the streak, hardness, cleavage, luster and other special physical properties of these and other minerals. If you cannot see any of a mineral (no powder is produced) it has no streak. If you see a white powder, the mineral has a white streak, which is not the same as having no streak. Otherwise, describe, as specifically as possible, the color of the streak. Small variations are important! When asked about LUSTER: answer metallic or nonmetallic. When asked about, answer with a number 1-10 or a small range (i.e., 4-5). Verify and write the exact hardness listed in your Manual in the space provided! REMEMBER to double check with the hardness listed in your lab manual! Use your glass plate, fingernail, MOHS SCALE OF, etc. to determine hardness. When asked about CLEAVAGE, give the number of cleavage planes and the angle(s) between them. If a sample does not have cleavage write FRACTURE in the space provided. Sometimes the cleavage surfaces are too small to see clearly, in which case cleavage may be Not Prominent. When asked about FEEL answer earthy, greasy, glassy, chalky, soapy, etc. SPECIAL PHYSICAL PROPERTIES include: reaction with acid (HCL), reaction with acid (HCL) if powdered, very high specific gravity (density), magnetism, salty taste, specific odor, ability to burn, striations on cleavage plane, and intergrowth patterns (veinlets), and double refraction. Use Table 1.2 to determine if the mineral has an economic use or if it is just a common rock forming mineral. You will need to be able to determine these physical properties and use them to identify these minerals for this laboratory assignment and for the Mineral Exam. USE THE TABLES PROVIDED IN YOUR LABORATORY MANUAL TO HELP YOU IDENTIFY THE SAMPLES. You may have some minerals that show up more than once!!!! See Table 1.1 of your manual for information on minerals with Economic uses. List of Possible Minerals: Augite Biotite Calcite Chalcopyrite Gypsum Halite Galena Garnet Hematite (see figure 1.8 [8 th ed.]): Specular Hematite [right sample] and Oolitic Hematite [left sample]) Hornblende (Amphibole) Limonite Magnetite Muscovite Olivine Pyrite Quartz (Color Varieties: Amethyst, Citrine, Milky, Rose, Smoky, etc.) Fluorite Graphite Kaolinite Plagioclase feldspar Sulfur Potassium feldspar You may not see all of the varieties listed above! Talc Instructor: Ms. Terry J. Boroughs 3

4 SAMPLE A. LUSTER SAMPLE B. LUSTER SPECIAL PHYSICAL PROPERTY SAMPLE C. LUSTER Be Specific!! SAMPLE D. LUSTER Instructor: Ms. Terry J. Boroughs 4

5 SAMPLE E. Several varieties of this mineral are possible. Make sure you look at the different types! LUSTER SAMPLE F. LUSTER SPECIAL PHYSICAL PROPERTY SAMPLE G. LUSTER SPECIAL PHYSICAL PROPERTIES Instructor: Ms. Terry J. Boroughs 5

6 SAMPLE H. LUSTER SPECIAL PHYSICAL PROPERTY SAMPLE I. LUSTER SPECIAL PHYSICAL PROPERTY SAMPLE J. Notice the soapy or greasy feel of this sample. LUSTER Instructor: Ms. Terry J. Boroughs 6

7 SAMPLE K. LUSTER SPECIAL PHYSICAL PROPERTY(S) SAMPLE L. LUSTER SAMPLE M. LUSTER SAMPLE N. LUSTER CLEAVAGE or CRYSTAL FACES? (pick one) Instructor: Ms. Terry J. Boroughs 7

8 SAMPLE O. LUSTER SAMPLE P. LUSTER Be Specific!! SAMPLE Q. LUSTER SAMPLE R. LUSTER Instructor: Ms. Terry J. Boroughs 8

9 SAMPLE S. The color of this sample can be clear, white, green, yellow, purple, or blue. LUSTER SAMPLE T. LUSTER SAMPLE U. LUSTER CLEAVAGE or CRYSTAL FACES? (pick one) SAMPLE V. LUSTER Special Physical Property Instructor: Ms. Terry J. Boroughs 9

10 SAMPLE W. LUSTER SAMPLE X. This mineral forms cubic crystals, these cubes are crystals not cleavage! LUSTER The following questions are extra credit points! THE FOLLOWING QUESTIONS REFER TO THE SUMMARY / REPORT PAGE in chapter 1. (Read the questions from your manual and place your answers in the following spaces provided.) 1. Name the physical property (hardness, color, etc.) described by each of the following statements. A red-colored powder on unglazed porcelain: Breaks along smooth planes: Scratches glass: Shines like a metal: 2. What term is used to describe the shape of a mineral that has three directions of cleavage that intersect at 75 and 105 degrees? 3. Describe the cleavage of these minerals (include both the number of directions and angles between): Calcite: Muscovite: Halite: Potassium and plagioclase feldspar: Instructor: Ms. Terry J. Boroughs 10

11 The following questions are extra credit points! 4. What physical property most distinguishes biotite mica from muscovite mica and how you can tell them apart (be specific!) 5. Name a mineral that exhibits the physical property listed below. (Use the photos in this chapter, if needed.) More than one mineral may exhibit the physical property. In other words, identify a mineral that would exhibit that particular physical property. Metallic Luster: Fracture: One Direction of cleavage: Striations: Multiple colors: Cubic cleavage: Non metallic luster: 6. If a mineral can be scratched by a penny but not by a human fingernail, what is its approximate hardness on Mohs scale? 7. Identify minerals that exhibit a special (as in unusual or not typical and/or specific to an individual mineral) physical property and identify the specific special property associated with that mineral. Mineral: Mineral: Special Property: Special Property: 8. Provide an economic use for each mineral listed below: (In other words what use is it mined for?) Galena: Hematite: Graphite: Sphalerite: Gypsum: Calcite: 9. Identify several minerals and identify the specific hardness associated with that mineral. Mineral: Mineral: Hardness: Hardness: The End! Instructor: Ms. Terry J. Boroughs 11