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LAB Mineral identification

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LAB Mineral identification Powered By Docstoc
					Earth Science                                           Name_____________________________
Mineral Identification Lab                              Date_________________Pd_____#____


Introduction:
       A mineral in Earth science is different from the minerals in the foods we eat. A mineral is
a naturally occurring, inorganic solid with an orderly crystalline structure and a definite chemical
composition. Minerals form nearly everywhere on Earth under different conditions. For
example, minerals called silicates often form deep in the crust or mantle where temperatures
and pressures are very high. Most minerals known as carbonates form in warm, shallow ocean
waters. Most clay minerals form at or near Earth’s surface when existing minerals are exposed
to weathering. Still other minerals form when rocks are subjected to changes in pressure or
temperature.
       In this lab you will use your qualitative observation skills to describe the features of some
of the most common minerals. At each lab station you visit you will observe the group or
groups of minerals present and answer a set of questions about each. In your lab book your
lab report will contain a title, purpose, vocabulary list, and a page for each lab station. Each
page should be clearly labeled to show the table number, mineral group represented,
procedures for that particular station, and questions (with space below each to answer) written
out. You will answer the questions as you make your observations at each station. The last
page of your lab will contain the conclusion questions for the Mineral Identification Lab.

Vocabulary: mineral, inorganic, silicate, carbonates, oxides, sulfates and sulfides, halides,
native elements, streak, luster, crystal, hardness, cleavage, fracture, density

Procedure: Examine the minerals at each station and answer the following questions based on
the samples and literature available.
Station 1: Silicates
      1. List the names and colors of each of the feldspar samples.
      2. Look at each of the samples: Do they show cleavage or fracture? Explain.
      3. Describe how orthoclase & plagioclase are different, both physically and chemically.
      4. What are feldspars commonly used for?
      5. Describe how the biotite & muscovite micas are different.
      6. Hold a single sheet of each up to the light & record your observations.
      7. Why is color not a useful way to identify quartz?
      8. What is quartz used for?

Station 2: Silicates
      1. List the names of olivine, hornblende, and serpentine and describe the color, luster,
         and cleavage of each of the samples.
      2. Is cleavage a good identification tool for these particular samples? Explain why?
      3. How is olivine distinct from these other samples?
      4. Observe the hand sample of garnet. Use the stereo microscope to examine the
         crystals. Sketch one of the crystals showing the best face.
      5. Examine the crystals in the cases. DO NOT OPEN THE CASES! Describe the
         differences in the crystal samples.
      6. Explain how the samples of talc different from the other silicates at this table.
Station 3: Carbonates and Oxides
      1. Observe the 3 samples of calcite; list the colors, luster, and cleavage of each.
      2. On the “TEST ONLY” sample, put 2 drops of dilute HCl. (Be extremely careful with
         the hydrochloric acid and wash your hands thoroughly after completing this test.)
         Observe the results. Wipe the sample and any excess off with a paper towel and
         leave the sample for the next group. ONLY TEST THE LABELED SAMPLE!
      3. Use the large hand sample of calcite and put the sides with the X together. Take
         them apart again and observe the cleavage surfaces. (These were created with 1
         strike of a hammer.)
      4. Examine the sample of dolomite. Record observations in comparison to calcite.
      5. Observe the samples of beryl. Describe & give the differences from the gem quality
         samples as shown in the book.
      6. Use the paperclips to explain the special identification property of magnetite.
      7. Examine the sample of hematite. Describe the color, luster and streak. Test the
         small sample only.

Station 4: Sulfates & Sulfides
      1. How are barite & gypsum different from the other samples at this station? Use the
         physical properties of the minerals and information from the text.
      2. Describe the density of galena compared to an equal sized piece if gypsum.
      3. Describe the crystal habit of galena. How many cleavage planes does it show?
      4. Compare the color and luster of galena and pyrite.
      5. Using the stereo microscope examine the crystal habit of pyrite and galena. Sketch
         and label each showing the surface features you observe.
      6. Examine the samples of chalcopyrite (blue) and arsenopyrite (purple). How are these
         different from the samples of regular pyrite? What might cause this difference?

Station 5: Halides
      1. Compare the colors and luster of the fluorite samples. Is color a good way to identify
         fluorite? What might be a better way?
      2. Examine the fluorite crystal in the box. Sketch this sample showing as many sides as
         possible and label the 3 cleavage planes.
      3. Using the dark purple hand sample, sketch 1 crystal & show the cleavage planes with
         at least 1 angle.
      4. Examine the 3 samples of halite. Do not open either sealed container. Compare
         and contrast their colors, textures, and crystal shapes.
      5. How were these 3 halite samples formed? Use the text as a reference.

Station 6: Native Minerals
      1. Examine the graphite samples. Do a streak test on the small sample. Record the
         color, luster and streak.
      2. Examine the copper and sulfur samples. Compare their color luster and smell.
      3. Use the stereo microscope to examine the gold vein in sample #11. Record your
         observations.
      4. What is this other mineral that the gold seems to be embedded in? What mineral
         does gold usually form with?
Station 7: Crystals and Mineral Ores
      1. Examine the samples of hematite (12), limonite (13), magnetite (14), pyrite (15), and
         specular hematite (18). These are iron ores. Make a table to describe their
         characteristics. Include color, luster, and mineral group.
      2. Examine the samples of azurite-malachite (1), chalcopyrite (7), and native copper (9).
         These are copper ores. Make a table to describe their characteristics. Include color,
         luster, and mineral group.
      3. Examine the geodes. How are they similar? Note color, luster, and crystal structure
         in your observations.
      4. Examine the quartz crystals and Herkimer diamond. Describe the color, luster and
         crystal shape of each. What makes the Herkimer diamond unique?

Conclusion Questions: Answer in complete sentences.
     1. What is the distinction between cleavage and fracture?
     2. Why is color alone not a reliable means of identifying a mineral?
     3. Why is streak a more reliable property than color in mineral identification?
     4. What mineral is usually identified by using the acid test?
     5. List the properties which are most useful in identifying minerals.
     6. Why are other mineral properties less useful for identification?



      Mineral Luster Terms
             Term                                    Definition
     Adamantine          very gemmy crystals
     Dull                just a non-reflective surface of any kind
     Earthy              the look of dirt or dried mud
     Fibrous             the look of fibers
     Greasy              the look of grease
     Metallic            the look of metals
     Pearly              the look of a pearl
     Pitchy              the look of tar
     Resinous            the look of resins such as dried glue or chewing gum
     Silky               the look of silk, similar to fibrous but more compact
     Vitreous            the most common luster, it simply means the look of glass
     Waxy                the look of wax

				
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posted:11/22/2011
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