Caves are packed full of minerals. These mineral deposits form unique shapes that
appear like icicles. They come in two forms stalactites which grow down from the ceiling.
And stalagmites which grow up from the ground. In this cool science experiment we will
grow our own Stalactites and Stalagmites.

Materials Needed  To Make Stalactites:

  • Some Yarn or String
  • Epsom salts
  • Baking soda
  • Four Metal washers
  • Four small glass jars or plastic cups

Process to Make Stalactites:

1) First measure out (6) two foot pieces of yarn or string and cut it off. Take (3) two foot
pieces of yarn or string and braid them together. Tie a metal washer to the end of each
side of the braided strings. Repeat braiding and washer process for remaining (3) pieces
of string or yarn. The metal washers will serve as weights to keep the ends of the yarn or
string in the glass jars.

2) Get some very warm or hot water (120-140 degrees) and fill one of the glass jars 2/3 of
the way full. Start stirring in baking soda. The idea is to make a super saturated solution in
which you keep stirring in baking soda until it will no longer dissolve. Dissolve in as much
baking soda as you can! Do the same process with a second jar and more baking soda.
Repeat the process with the two remaining jars and Epsom salt. You can add food
coloring to your solution to form colorful cave formations.

3) Find a warm place and let the jars sit for a couple days. Next place one end of the
braided string into a glass with baking soda solution and let the washer sit on the bottom.
Put the other end of the braided string or yarn into the other glass of baking soda solution
with washer at bottom (see image below).  Repeat process with Epsom salt glasses,
braided strings or yarn and washers. Arrange the cups so the strings hang down in a "U"
shape. Place a plate under the "U" shape between the glasses.

4) Leave the glasses in a warm dry place for several days. You will start to see tiny
Stalactites forming down from the string and tiny Stalagmites forming up from the plate.

The Science Behind Making Stalactites and Stalagmites:

Stalactites and Stalagmites are columns of stone that grow in caves. They form when
mineral deposits dissolve in rainwater and then drip slowly from the roof and walls of
underground caves. As the rainwater evaporates, it leaves only the mineral deposits
(calcium carbonate) which forms these icicle like shapes. In our experiment we used
baking soda and Epsom Salt as the dissolved minerals. As the mineral water soaked up
onto our strings or yarn, dripped, and evaporated Stalactites and Stalagmites were
formed!  Now go grab some friends and make some cool cave formations.
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