Adapted with permission by Adrienne Barnett, Chabot Space & Science Center, Oakland, California.
"Thar's gold in them thar classrooms!" History meets Earth science in the fun, hands-on activity below.
Some gold deposits, or lodes, are found in veins of fractured rock. After millions of years of weathering, gold nuggets and flakes are eroded out of the veins and carried away by streams and rivers. Gold is 19 times heavier than water and tends to settle on the bottom and in the bends of rivers, streams, and lakes with sand and gravel, forming deposits called placer. From Georgia to California and Alaska, it is in these deposits that adventurous fortune seekers have panned for gold during the gold rushes of the 1800s. Some are still trying their luck today.
- Plastic container, wading pool. or preschool sand-and-water table (at least 9 inches deep with hard sides)
- 7-10 "gold pans" (pans with ridges on the side are easier for children to work with) or tin pie pans
- 10-20 lbs. playground sand (amounts of sand and materials below may vary based on size of container and budget)
- 5 lbs of 1 inch mixture of pebbles
- 5 lbs of ¼ inch mixture of pebbles
- Up to 30 gold pieces, or substitute copper BBs
- 30-60 pieces of 1inch pyrite ("fool's gold")
- 30 minerals such as quartz, garnet, amethyst (optional)
- Iron filings or crushed magnetite (optional)
- Plastic tarp (optional)
- 1/2 cup of bleach
Prepare to create a "gold-bearing river." If indoors, place your plastic container over a tarp. Mix sand, pebbles, minerals, pyrite, and magnetite together in the "river container" until 2-4 inches deep. Crushing the minerals into small pieces is recommended.
Rinse the mixture several times with water. Then add 3-4 inches of water, leaving 3 inches of space from the top.
Sprinkle on 5-30 gold pieces or BBs, depending on your budget. You now have a gold-filled river! For fun, name it after a local gold-bearing river.
To prepare to pan for gold, fill the gold pan with the sand/gravel mixture, keeping the pan under the water.
Vigorously shake the pan back and forth. Since gold is a heavy mineral, the shaking will help it settle to the bottom of the pan. After 30 seconds of shaking, bigger pebbles will rise to the surface of the pan. Carefully scrape them off and put them back in the "river."
Repeat the previous step until you are left with only small pebbles and sand.
Now it is time to start removing the sand. Tilt your pan away from you (if you have gold pans with ridges, point the ridges away from you). Dip your pan in and out of the water at a 40 degree angle. Sand and gravel will fall out over the rim. Continue until only a small amount of fine-grained sand is left in the pan.
Add a little water and move your pan with a slight circular motion. The fine sand will move to the other side of the pan exposing any gold. If you found gold yell out, "Eureka!"
To pick up the gold pieces use a dry fingertip. Place the gold in a vial or a plastic bag. Try your luck again!
When finished, add 1/2 cup of bleach (with adult supervision) to clean the "river," drain, and let air dry until next use.
For an extra activity: Identify the minerals in the pans. Use magnets to find magnetite.