Stalagmites and Stalagtites

Make your own Stalactites and Stalagmites



Make your own Stalactites and Stalagmites

Stalactites and stalagmites are both mineral formations that develop in limestone caves. One comes down from the ceiling and the other comes up from the floor; which is which? A good way to remember is their spelling. Stalactite has a “C”, for ceiling and stalagmite has a “G”, for ground. The stalagmite comes up from the ground and the stalactite comes down from the ceiling. They are both formed when water dripping from the ceiling leaves traces of calcite and as the water evaporates, the calcite is left behind to form a stalactite. When the water hits the floor, the same thing happens and the stalagmite begins to grow up. Over time, the stalactite and stalagmite often grow to meet each other and form a stone column in the cave.

You can re-create this occurrence in your own home with just a few household products and some patience.


  • Two glass jars (pint canning jars work well)
  • A saucer or glass plate
  • Natural fiber yarn or twine (cotton or wool will both work)
  • Epsom salts or baking soda
  • 2 medium sized fishing sinkers or something similar to weigh the ends of the string down


  1. Fill both of the jars with very hot tap water.
  2. Dissolve as much baking soda or Epsom salts as you can into each jar (it may take a lot) until the liquid is completely saturated (won’t hold any more).
  3. Twist two or three strands of your natural fiber together and attach your fishing sinkers or other weight to each end of the string.
  4. In a warm place, set the two jars side by side about 6 inches apart and place the saucer or plate in between them.
  5. Place one end of each string into a jar making sure that at least two inches of the string is submerged and that the string hangs down in between the jars rather than being stretched tight. The lowest part of the string should only be a few inches above the saucer. After some time, the solution from each jar should soak into the string and drip from the lowest section of string onto the saucer.
  6. Check on the jars periodically during the next few days and see what happens.

What will Happen?

Over a period of days, the dripping solution will leave behind traces of soda or Epsom salts as the water evaporates and you’ll notice a tiny stalagmite and stalactite beginning to grow. With time, the two may come together to form a single column the way it would in a cave. Your stalagmite and stalactite will be much more fragile than those that form in caves however.

If you have time, a very similar project is growing your own crystals, and making sugar candy.



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