JoAnn Coburn
The Cleveland Museum of Natural History
1 Wade Oval Drive, University Circle
Cleveland, OH 44106

Level: Grades 4 - 8

Estimated Time Required: 45 minutes

Anticipated Learning Outcomes


The purpose of this activity is to demonstrate how individual subjective taste is a factor in value (in terms of cost) in gemstones, which have their origin in the natural realm of minerals. Gems are also an exciting and intriguing aspect to the study of minerals which can help to spur flagging interest and lead to deeper understanding of mineral and crystal formation.



  1. Fill bags ahead of time with 3 or 4 samples for each student. Bags cannot be filled with the identical mix of stones. Variety is important for activity.
  2. Discuss minerals in general. (This may be done in previous classes.)
  3. Discuss gems - i.e. natural minerals that have been cut, shaped and polished for human adornment or use. To qualify as a gem, a mineral must possess beauty (of some kind), durability, and rarity.
  4. Show bags to the students. Tell them that the stones are all genuine gemstones. Give them the conditions of the trading activity.

    They should look at their own stones and decide which, if any, they like. They will then have an opportunity to trade with others. They will have 10 - 15 minutes to move around the room and see what they might like better. Any trade of stones that both parties agree to is OK. One-for-one, two for one, etc. is fine as long as both parties agree. Salesmanship may be an important part of getting others to agree to a trade. Don't talk down your own stones and then expect someone else to want them. No other commodities other than the stones may change hands; trading involves only the stones.

    At the end of the time, they may choose and keep one, and only one, of the stones that they have in their possession.
  5. After these instructions, pass out the bags and allow the students time to move around and trade stones. Be prepared to have students ask what each stone is. I do not give out that information at this point. Many students will have at least heard the names before. What they hear will color their reaction and their judgement. For this part, it is better if they simply go by what they like.
  6. When the trading activity seems to be slowing down, give them verbal warning that time is running out and then call for a return to their seats. Ask students about their trading activity. You might want to see how many have only one stone left and how many have parleyed their number up to six or more.
  7. Have students choose the stone in their possession that they want to keep. That sounds easy; it is not! Be prepared for agonizing over the decision. They should put the one they want back in the bag. You may then go around and collect the rest.

Results and Discussion

  1. Take some time for discussion of their choices: what they chose and why.
  2. At long last, name the various types of stones that were present in the samples. Groans and moans! All will want to know what the stones are worth as they hear names like amethyst, tigereye, garnet, agate, etc. As you will know, having purchased the material, almost all can be had for 10 - 25 cents apiece or less. This will also be a shock.
  3. Discuss why these chips and pieces are not as expensive as they expected:

Related Activities

With careful observation of their students during the trading period, teachers may gain some interesting insights!

Recommended Reading for Teachers

BRUTON, E., 1986, Legendary Gems or Gems That Made History, Chilton Book Co.

DIETRICH, R.V., and SKINNER B.J., 1990, Gems, Granites and Gravels, Cambridge University Press, p.. 27-29.

Planet Earth series, Time-Life Books, 1983, Gems.

SCHUMANN, W., 1977, Gemstones of the World, Sterling Publishing Co., Inc., NY.

Recommended Reading for Students

STANGLE, J., 1990, Crystals and Crystal Gardens You Can Grow, Franklin Watts.

SYMES, R.F. and HARDING R.R., 1991, Crystal and Gem, Eyewitness Books.

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