Crystal Formation

By Cibao Chua

1.  What is a crystal?

A crystal is a solid object which is made up of an ordered repeating pattern of the same atom or

2.  What substances can be used to make crystals?

3.  What are some examples of crystals in nature? What household items can you also grow
crystals from?

You can use salt or sugar to grow crystals

4.  Explain the process of crystal growth.

5.  Explain how crystals can grow in different shapes and sizes.

Crystals grow into certain shapes because the atoms or molecules join together in a pattern that repeats itself over and over to create a certain shape. A crystal grows by adding atoms or molecules to all its sides in the exact same pattern as the atoms and molecules that were added before. Because each different crystal is made up of a different building block (atom or molecule)they each
have a different structure or shape. This is why salt crystals are square in shape while Epsom salt crystals are long and rectangular.

6.  Outline a few different types of crystals.
 Sugar, Salt, Diamond, Snow Bath salts, Quartz

7.  What effect do crystals have on light travelling through them? (relate to reflection, refraction, dispersion and diffraction)

8.  What are the optimum conditions for crystal growth?

It is best for crystals to  stand in a draft free location, not in direct sunlight or near a heater. The
aim is to keep the temperature as constant as possible.


Day 1:

25g of potash alum
2 beakers
170 mL of hot water
Stirring rod
Filter funnel
Filter paper
Watch glass/filter paper

1.Make sure all apparatus is clean and dry.

2. Place approximately 25 g of potash alum in a beaker (250 ml or bigger) and add approximately 170 ml of hot water.

3. Stir the mixture until all the crystals have dissolved.

4. Filter the warm solution through a filter funnel (in which filter paper has been inserted) into another clean beaker.

5. Cover the beaker of solution with the watchglass or fresh filter paper and set aside in a cool sheltered place and allow it to stand undisturbed overnight.

6. The first beaker and funnel can be washed and dried and the residue and filter paper used for filtration discarded.

7. Take photos and measure levels

Day 2:

Plastic spoon/ spatula/ tongs /tweezers
Loose fitting paper hat

1. (The next day) Observe the beaker of solution.

2.  Carefully decant the clear solution above the crystals into a clean beaker and set it aside for
later, leaving the crystals behind in the other beaker.

3.  From the bed of crystals, one good symmetrical crystal or group of crystals needs to be selected to act as “seed” for your big crystal.

4.  Using a plastic spoon, spatula, tongs or tweezers, transfer the selected crystal to the beaker containing the decanted solution,trying to place it centrally in the beaker.

5.  Cover the solution with a loose-fitting paper hat that permits water to evaporate slowly whilst keeping out dust.

6.  Take photos and measure levels

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