5. MINERAL PROPERTIES, IDENTIFICATION, & USES

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1 LAST NAME (ALL IN CAPS): FIRST NAME: 5. MINERAL PROPERTIES, IDENTIFICATION, & USES Instructions: Refer to Laboratory 3 in your Lab Manual on pages to answer the questions in this work sheet. Your work will be graded on the basis of its accuracy, completion, clarity, neatness, legibility, and correct spelling of scientific terms. If you want to test a mineral for effervescence and want to apply HCl, you must first ask permission from your instructor (remember HCl is an acid and is hazardous to health). Some minerals that you would be working with may have sharp edges and corners, therefore, be careful when working with them! When you are done with your lab work, please clean the desk and leave all materials you worked with in the same way you found them! INTRODUCTION MINERALS are inorganic, naturally occurring solids that have a definite chemical composition, distinctive physical properties, and crystalline structure. PHYSICAL PROPERTIES OF MINERALS COLOR A mineral s color is usually its most noticeable property and may be a clue to its identity. Minerals such as galena, sulfur, olivine and gold have each a typical color. Galena gray; Sulfur yellow; Olivine green Many other minerals show a range of colors: For example, quartz comes in the following colors: clear, white/milky, purple, gray/smoky, red/rose CLARITY OF MINERALS: Clarity refers to a mineral s ability to transmit light. Transparent: clear and see-through, like window glass Translucent: foggy, like looking through a steamed-up shower door Opaque: impervious to light, like concrete and metals MINERAL HABIT: A mineral s habit is the characteristic crystal form(s) or combinations (clusters, coating, twinned pairs) that it habitually makes. LUSTER refers to the way a mineral surface reflects light. Minerals that shine like metals have metallic luster, all others have non-metallic luster. Examples: Metallic luster: new coins, knife, keys, jewelry, aluminum foil. Non-metallic luster: glass, candle, pearl, porcelain STREAK is the color of a mineral or other substance after it has been ground to a fine powder. The easiest way to do this is by scraping the mineral against an unglazed ceramic plate (streak plate). Calcite Color: white, pink, or clear; Streak: white Hematite Color: black; Streak: brown Pyrite Color: brassy; Streak = dark gray If a mineral is harder than the streak plate (H=6.5), it will scratch the streak plate and make a white streak of powder from the streak plate. Page 1 of 5

2 HARDNESS A mineral s hardness is a measure of its the resistance to scratching. Please memorize all 10 minerals of the Mohs Scale of Hardness. CLEAVAGE The tendency of a mineral to break (cleave) along flat, parallel surfaces (cleavage planes). Cleavage planes are surfaces of weak chemical bonding (attraction) between repeating parallel layers of atoms in a crystal. OTHER (SPECIAL) PROPERTIES REACTION TO ACID (Effervescence): The vigorous bubbling (fizzing) that results when calcite reacts with dilute HCl. DOUBLE REFRACTION: refers to double image produced when you view an object through calcite. MAKING GRAY MARK: Graphite (it s the lead in pencils) is the only mineral that leaves grey mark on paper STRIATIONS: these are thin parallel corrugations or stripes found on the cleavage surfaces of only two minerals, plagioclase and pyrite MAGNETISM: A property shown by magnetic substances when they are sufficiently magnetized. Magnetic substances attract magnets and other iron objects. The mineral magnetite acquires strong magnetism when it forms. It is the only magnetic mineral known. Q1. QUESTIONS I) Name a mineral that always shows one color and can be identified solely on the basis of its color: II) Say True/ False: Minerals are crystals that are always clear and see-through, like window glass. Q2. Name the elements or compounds that make up the following minerals. Refer to the Mineral Database given in Figure 3.21, on pages as needed. I) Quartz: II) Halite: III) Diamond: IV) Calcite: Q3. What is the streak of each of the following substances? Refer to the Mineral Database given in Figure 3.21, on pages as needed. I) Graphite (pencil lead): II) Wheat: III) Salt: IV) Charcoal: V) Quartz: VI) Muscovite: Q4. Determine whether the luster of each of the following materials is metallic (M) or nonmetallic (NM). I) A brick: II) Butter or margarine: III) A seashell: IV) Sharpened pencil lead: V) Ice: VI) A mirror: Page 2 of 5

3 Q5. A mineral can be scratched by a knife blade but not by a wire (iron) nail (Figure 3.9). I) What is the hardness number of this mineral on Mohs scale? II) Is this mineral hard or soft? III) What mineral on the Mohs Scale of Hardness has this hardness? Q6. A mineral can scratch calcite, and it can be scratched by a wire (iron) nail. I) What is the hardness number of this mineral on Mohs scale? II) What mineral on Mohs scale has this hardness? Q7. An unknown mineral is scratched by a piece of quartz and is able to scratch a piece of fluorite. What is its hardness or possible range of hardness? Explain how you determined the hardness. Q8. The brassy, opaque, metallic mineral in Figure 3.7A is the same as the mineral in Figure 3.8. I) What is this mineral s hardness, and how can you tell? II) What is the crystal habit of this mineral? [Refer to figure 3.4, page 78] III) Based on the Mineral Identification Tables (Figs , pages 90-92), what is the name of this mineral? IV) Based on the Mineral Database (Fig 3.21, pages 93-97), what is the chemical name & formula for this mineral? V) Based on the Mineral Database (Fig 3.21, pages 93-97), how is this mineral used by society? Name 2 uses. Q9. Analyze the mineral given in figure Determine the mineral s hardness and its name. Justify your answer. Page 3 of 5

4 Q10. Determine how many cleavage/s each of the following minerals possess. Refer to the Mineral Database given in Figure 3.21, on pages as needed. I) Calcite: II) Halite: III) Fluorite: IV) Galena: V) Muscovite: VI) Quartz: VII) Gypsum: Q11. (I) Refer to the list of selected net non-fuel mineral resource imports by the USA in 2012 (Figure 3.22). Based on Figure 3.22 complete the Table below. (II) Would the USA be able to manufacture cell phones if a world crisis prevented it from importing minerals and elements? YES, or NO? Circle your answer & discuss your evidence using info from the caption to Fig Page 4 of 5

5 Q12. For the 6 minerals provided by your instructor, determine the physical properties indicated for each. If a physical property cannot be determined with the given tools or methods discussed in lab/class, write Can t be determined. For CLEAVAGE, write the # of cleavages present as 1, 2, 3, etc. If the mineral does not have any cleavage, write None. For OTHER PROPERTIES use only the following terms, when applicable: magnetism, striations, making grey marks on paper (like the lead in your pencil), double refraction, effervescence. SAMPLE # 4 LUSTER: STREAK: SAMPLE # 5 COLOR: HARDNESS: SAMPLE # 6 STREAK: LUSTER: SAMPLE # 8 HARDNESS: SAMPLE # 13 SAMPLE # 14 Page 5 of 5