THE WILD WEST: All That Glitters
For 20th-century prospector Chuck Fipke, a "crazy" idea may become the find of a lifetime. Fipke turned his knowledge of geology into a 15-year treasure hunt. The site he is exploring in Canada may ultimately surpass any other diamond mine on the earth. Using science, technology and pure grit, Fipke stuck with his conviction that diamonds lay deep under the surface of the Canadian wilderness. His determination and luck may reward Canada with the most valuable and rarest of all gems.
Activity 1: Growing Crystals
Activity 2: Happy Tailings To You!
For Further Thought
ACTIVITY 1: GROWING CRYSTALS
All minerals fit into a particular crystal shape. Think of the last time you saw crystals of salt. The small cubes are a distinctive characteristic of the mineral halite. In fact, both halite and table salt belong to the cubic crystal system. No matter how small (microscopic) or large (macroscopic) the crystal, it is always a cube. Some cubes are as big as your fist!
Small crystals grow in igneous rocks that cool relatively quickly. Larger ones take more time, so they grow in igneous rocks that cool slowly. Diamonds are found in a matrix of kimberlite, a vein or pipe of molten rock formed deep underground. Over millions of years, heat and pressure transform carbon into diamonds. Kimberlite pipes rise up out of the magma to the earth's surface, pushing diamonds and other minerals to the top. Though diamonds exist in other sites, Fipke's find is the first in the Western Hemisphere.
Each of the six crystal systems has its own geometric crystalline shape different from all others. Diamonds belong to the isometric system. They occur in nature as octahedral, dodecahedral or cubic shapes.
In this activity, you will grow crystals of the same substance over different periods of time; evaporation of water is analogous to heat loss in a large body of rock.
- salt (kosher salt, Epsom salt, sugar, potassium chloride or any other safe salt)
- filter paper
- beakers or pot
- clear container
- shallow baking pan
- hand lens
- microscope and slide (optional)
- Choose one or more salts; crystallize them separately.
- In a pan or beaker, heat about 2 cups of water to boiling. Stir in as much of the salt as you can. Stop adding salt when no more will dissolve. At this point, take a drop of the hot mixture and examine it with a microscope to watch the formation of microcrystals. Prepare and observe three different mixtures:
Mixture #1: Pour half a cup of the saltwater mixture into the baking pan. Set it aside in a place where it won't be disturbed until all the water has evaporated.
Mixture #2: Pour 1 cup of the original mixture into a clear heatproof jar or beaker and allow it to cool to room temperature. Sprinkle a few crystals of salt into this mixture. Cover with several thicknesses of cheesecloth.
Mixture #3: Filter any crystals from the original mixture and return the clear liquid to a pan or beaker. Put it back on the heat source (be sure to watch glass beakers carefully during this process). Stop heating when the liquid seems to be almost completely evaporated. Cool and cover with newspaper. Set aside.
- Observe all three mixtures daily until you have a substantial number of crystals in the clear jar.
- Examine crystals with a hand lens or microscope.
- Compare and contrast crystals grown at different rates.
- Which crystals seemed to be most perfect?
- Speculate on the result if you were to use thread to hang one perfect crystal in the clear jar (better yet, try it!).
ACTIVITY 2: HAPPY TAILINGS TO YOU!
Worldwide mining operations rely on people who can distinguish between "trash" minerals and those that will net a profit. For example, to the untrained eye, diamonds in the rough may look like glass. In fact, rookie diamond thieves in South Africa have mistakenly stolen quartz in favor of raw diamonds! Diamonds can be sifted out from their native kimberlite, but may be missed if mixed in with other glassy minerals, especially in less sophisticated techniques than those seen on FRONTIERS.
Sometimes it's hard to separate desirable minerals from undesirable ones, especially if they look alike or the crystals are of similar sizes. Old, worked-out mines contain some desirable minerals (in small quantities) mixed in with unwanted minerals, but that doesn't stop some people from trying to squeeze out the last drop. Once considered tailings (or trash), the mix may now be profitable for mining. Desirable minerals can be separated physically and chemically.
In this activity you will prepare a sample of tailings, then "mine" and separate out desirable materials using whatever method(s) you choose, and quantify the results.
- mine tailings (see 'PROCEDURE')
- magnet covered with a sleeve of paper
- sieves or strainers
- filter paper
- magnifying glass
- pan balance or triple beam balance
Before mining, prepare the tailings as follows. Combine known masses of the following: two different colors of fish tank gravel, perlite or similar sized flaked styrofoam, iron filings, white sand, table salt. Determine the percentages and specific ingredients of your tailings mix. Be sure to record the masses of the different ingredients before mixing. Then record the mass of the entire mixture.
Designate some of the "minerals" as "recoverable" ("salable"). For example, you might decide to make the following mix -- salt (1), iron filings (2) and one color of fish tank gravel (3) -- as recoverable materials.
- Working in pairs, obtain a sample of mine tailings and examine it very carefully. Determine the mass of your sample. Decide which materials you want to separate and catalog for possible "mining."
- Carefully sketch every material type (not every grain) you find in the mix. Record colors and shapes in a data table. Determine the number of different materials present in the sample.
- Identify the recoverable materials and decide how you are going to separate them from the unwanted ones.
- Separate the recoverable materials and record the mass of individual materials.5. Combine your salable product masses with all others in the class. Record the totals for each. Assume 1 gram equals 1 ton. Convert all gram measurements to tons and record.
- Recoverable materials should constitute no more than 25 percent of the total tailings mass. This way, you can build the activity so you see a profit or a loss, whichever ingredients you choose. (See Question 1, below.)
- Salt is recovered in solution after other materials are manually separated with a magnet and tweezers. Salt solutions can be left to sit or gently boiled to evaporate water.
- You will get better results separating the iron filings if you wrap the magnet in a paper sleeve. When the sleeve is removed, the filings drop off.
- Assume that the material you recovered sells for $6,000 per ton (material 1), $4,000 per ton (2) and $2,000 per ton (3). If it costs you $2,000 per ton of tailings to produce the materials and dispose of the waste, what is the gross profit or loss on YOUR sample? What is the total gross profit or loss for the class?
- Write a letter to your company's shareholders explaining the results of your exploratory operation. If there is a profit, be sure to push hard for them to back your efforts.
- Determine quantities of recoverable materials originally placed in the mix. What percentage of materials were lost in recovery? Explain some techniques you could use to increase your yields.
FOR FURTHER THOUGHT
- Compare the geology of the earth's richest diamond-bearing kimberlite pipes: South Africa, Siberia, Australia and Canada's Northwest Territories.
- Where are diamonds located on the Mohs scale?
- What did Chuck Fipke have to know before beginning his search, and what do you think sustained him in his relentless quest to find diamonds in Canada?
- Some environmentalists are concerned that extensive diamond mining in Canada will disturb caribou migration routes. Do you think the benefits of finding a valuable resource like diamonds outweighs the risks to the environment? Compare the environmental impact of a diamond mine to a coal mine.
Scientific American Frontiers
Fall 1990 to Spring 2000
Sponsored by GTE Corporation,
now a part of Verizon Communications Inc.