Make Stalactites and Stalagmites

Caves are full of mineral deposits that form unique shapes, such as the icicle-like stalactites (which hang from the ceiling) and stalagmites (which rise up from the ground). (To learn more about cave rock formations, go to our Stalactites, Stalagmites, & Other Cave Formations Teaching Tip.) Make your own stalactites and stalagmites with this project! (Adult supervision recommended.)

Materials:

• String
• Epsom salts
• Baking soda
• Metal washers
• Four small glass jars or beakers

What to do:

1. Cut two 24" pieces of cotton string or wool yarn, and tie one metal washer to each end to act as a weight.

2. Fill four small glass jars or beakers 2/3 full with very warm (120-140 °F) water. Stir in as much baking soda into two of the jars as will dissolve; do the same with Epsom salt in the other two jars. Put the jars in a warm place where they can sit undisturbed for about a week.

3. Next, place a small plate between each set of jars and put the ends of one string in the baking soda jars with the middle of the string draping in a "u" shape just above the plate. Do the same with the Epsom salt.

After a few days, check to see if any material has built up on the string. An icicle-like formation should form downward on the string and upward on the plate. Real stalagmites and stalactites are formed in almost the same way, by mineral-containing waters dripping in caves until a deposit of calcium carbonate builds up...or down, as the case may be.

Website artwork, text and images Copyright © 2010 Home Training Tools, Ltd. All rights reserved.