It is easy, and a lot of fun, to make crystals. In this achievement activity, you will learn more about mineral crystals and you will learn how to grow actual crystals using some items that can be easily found in the house. Get your paper crystal models from the Making Crystals 1 activity. You will be able to compare the models with the actual crystals you grow in this activity.
Safety Note:This activity involves heating water. Therefore, work with an adult helper when you boil the water. BE VERY CAREFUL WITH HOT WATER...YOU CAN EASILY BE BURNED!
Activity preparation: Gather the following supplies: --Sauce pan(s) for heating water --A burner for heating water (stove, hot plate, etc.) --Salt --Alum --Spoons for spooning out salt and alum and for stirring --Pencils --String --Glass jars (for example, large baby food jars, jelly jars, mason jars, etc.) --Food coloring --Tweezers --Safety Goggles
Special Note:This activity will not bring instant results. You will be able to prepare up through Step 4 of each activity described below. The halite and alum solutions will have to sit for a number of days to allow the water to evaporate and crystals to form.
Activity 1: Growing Crystals In this activity you will actually grow real crystals.
Step 1: Heat a cup of water until it boils. REMEMBER TO BE SUPER CAREFUL WITH HOT WATER. SAFETY, SAFETY, SAFETY! Safety Note: We cannot over stress safety. Be sure eyes are properly protected. When working with boiling water, safety must be a top priority. Step 2: Stir in salt until no more salt will dissolve in the hot water. You will know that no more salt will dissolve in the water when you add salt and it just sinks to the bottom of the pan.
Step 3: Pour the salty water into a small, clear jar, like a baby food jar.
Safety Note: If the water is still very hot, be careful when you pour the water into the jar. A glass jar can shatter when its temperature changes very quickly. It is safer to allow the water to cool a bit in the pan before pouring it into the jars.
Note for Success: We have found that seed crystals grow much better in glass jars than in plastic containers.
Step 4: Place the jar in a warm room and wait. Let the water slowly evaporate from the jar. As the water evaporates, small square crystals of salt (salt is the mineral halite) will form on the bottom and on the sides of the jar.
Note for Success: Larger crystals grow when evaporation is slower. The evaporation rate can be slowed by covering the jar with a lid with holes punched in it (or with plastic wrap that has holes punched in it.)
Step 5: When a nice halite crystal has formed, carefully take it out of the jar, dry it off in a tissue, and save it for Steps 6-8. You might need tweezers to do this. Put the jar back in its safe place and let the rest of the water evaporate so the crystals in the jar can continue to grow. You will eventually have many nice halite cubes in the jar.
Step 6: Repeat steps 1-3. Let the salt water cool down to room temperature.
Step 7: Take a very thin thread and tie it around the halite crystal you saved in step 5. Tie the other end of the thread to a pencil. Make the thread long enough so that when the crystal hangs in the new salt water (step 8) it will hang in the middle of the jar.
Note for Success:You may want an adult to help you tie the thread on your small, seed crystals. These are called ”seed crystals” because they are the seeds around which larger crystals will grow.
Step 8: When the salt water is cool, let the crystal hang in the middle of the salt water. Place the jar aside and let the water slowly evaporate.
Note for Success:If you do not have a saturated solution, the seed crystal will dissolve when it is lowered into the solution. This is a common problem. Have patience and learn from the troubles; add more salt to the solution, and try again.
Check the crystal every day to see how much it has grown. When it stops growing, you can take it out, dry it off and display it. (The string will always be attached to it or you can cut it off if you wish). If you want your crystal to be even bigger, you can make another jar of salty water (repeat steps 1-4) and hang the crystal in the salt water for it to grow even more!
Activity 2: Growing More Crystals Repeat activity 1, but this time use alum. Alum will form 8-sided, diamond-shaped crystals. Mineralogists call these octahedral crystals. Alum crystals are usually very clear. You can buy alum at any drug store.
Note for Success:Alum crystals are generally clear and very well formed. After you have prepared your salt solution, prepare these alum solutions.
Optional - Activity 3: Colorful Crystals Repeat Activity 2 with alum, but this time, add a few drops of food coloring to create colorful crystals. Each club member can use a different color and then you can show him or her to one another when you are done.
Optional - Activity 4: Crystal Growing Contest Hold a crystal growing contest with your brothers and sisters, friends or classmates. The challenge is to see who can grow the largest and best-shaped crystal.