Epsom salt (magnesium sulphate) crystals are among the easiest and fastest to grow using equipment available in any science laboratory and even in your own home. Epsom salt itself is readily and cheaply available in most pharmacies.
To grow your epsom salt crystals you will need:
1) 1/2 cup of epsom salt
2) 1/2 cup hot water (about 70 degrees Celsius)
3) 1 narrow deep bowl
5) food colouring(optional)
1) Add small amounts of epsom salt to the hot water in the bowl, stirring continuously until no more crystals can dissolve in the solution. There should be a small amount of crystals left in the bowl. Add 2 drops of food colouring if desired.
2) Place the bowl in the refrigerator and do not disturb for 3 hours.
3) After three hours, the bowl will be filled with thin needle-like crystals.
The crystals grown using this method are quite fragile but long lasting. If food colouring is added, the colouring simply sticks to the surface of the crystal structure, but is not actually included within the crystals themselves.
To grow a single large Epsom salt crystal, the an evaporation technique is used, and this will take considerably more time than the method described above.
1) In a beaker containing 1/2 cup water at room temperature, dissolve as much epsom salt as possible, stirring continuously.
2) Warm the mixture to about 50 degrees Celsius (do not boil) and add more epsom salt until no more dissolves.
3) Add a few loose epsom salt crystals to the solution, and allow to cool for 24 hours in room temperature.
4) After 24 hours, excess epsom salt will have deposited on the loose crystals to form seed crystals in the beaker, leaving a saturated solution of dissolved epsom salt.
5) Carefully pour the saturated solution into a clean glass beaker. Do not allow any of the loose crystals to drop into the clean glass beaker.
6) Select the best seed crystal and add it to the saturated solution.
7) Cover the beaker with cloth to prevent dust from dropping into the solution, and place in an area where it will not be easily disturbed.
8) As the solution evaporated, the excess epsom salt will deposit on the seed crystal.
9) Check everyday to ensure that no 'rogue' crystals form on the seed crystal. If there are, pinch them off and rinse the seed crystal in a little bit of the saturated solution.
10) Allow the crystal to grow until it reaches the desired size.
Because evaporation is very slow, the crystal also grows very slowly, and this helps to ensure that the crystal is of a high quality.