Kids are attracted to crystals for their wide variety of aesthetically pleasing shapes and bright, pretty colours. Natural rock crystals take thousands of years to form, but crystals can be grown from chemicals in a couple of days at home or school for a fun learning project.
Crystallography is the scientific study of crystals and their structure. Crystals such as quartz and calcite are made up of trillions of mineral atoms or molecules arranged in a uniform pattern. The repeating patterns give the crystals their shapes and colours. Most crystals are clear with smooth flat sides and were formed millions of years ago deep inside the earth. Far underneath the crust it's very hot and the pressure is high which helps the crystals grow.
Natural crystals start off as solutions of dissolved or melted rock. These liquids full of the crystal particles are deposited in cracks and fissures in the bedrock of the earth. When the conditions are just right the crystals begin to slowly grow. There is an attractive force between the crystals' molecules and they start to stick together. Sometimes they do this by themselves, other times they start to grow by sticking to a small stone or piece of rock.
Sugar And Salt
If you look at salt or sugar under a microscope, you can see that it's made up of tiny crystals. Sugar crystals are oblong and slanted while salt crystals are like little square cubes. The crystals can be easily dissolved in water. The water evaporates and the sugar and salt will recrystallize in the exact same shape as before. The molecules and atoms stick together because of an attraction called an ionic bond.
Many crystals can be grown by kids as a science experiment or project. The materials can be bought as kits or acquired separately. The compounds grown into crystals include copper sulphate pentahydrate, nickel sulphate hexahydrate, sodium thiosulfate, sodium nitrate and potassium sodium tartrate. The chemicals are dissolved in a warm solution. A seed crystal is hung on a string in the liquid for the crystals to grow around as the solution cools. Kids can better understand the process of crystallisation by actually growing crystals themselves.