Though beautiful crystals can be grown from a variety of solutions, we are just going to look at salt for the moment.

Why would one bother to grow any crystal, much less salt crystals?

'Because you can', immediately springs to mind in response, but that's not the only reason.

If you have, say, copper sulphate in solution and want to extract its purest form you might use this method.

You can, of course, simply evaporate the solution but this may leave behind any other elements that may exist in the solution.

Looking at salt crystals is extremely important because its unwanted growth can cause enormous and costly damage to buildings and building materials.

Have you ever noticed, near the ocean, that some sandstone and bricks are all flaking away?

Salt laden moisture in the air soaks into the material, if it is not correctly treated, and the crystals grow inside the stone or brick, popping little pieces off as it does so.

This will occur in bricks that have not been 'baked' at a high enough temperature. All that aside, it is a pretty simple and inexpensive project for school.

Ingredients

• Cooking Salt

• About one litre of water

• Add the cooking salt to the water, while mixing, until no more will disolve.
• pour the bulk of your solution into the jar and put the cap on.
• Place the rest of the solution in the drying tray and carefully place where the water can evaporate off and it is out of the way of any possible rain.

• When all of the water has evaporated select the largest of the crystals you can see.
• Carefully tie your sewing cotton around it and connect the cotton to the square of cardboard so that the crystal hangs around midway down the solution in your jar.
• Leave for two or three weeks until a large salt crystal has grown.

If you wish to grow other types of crystals ask your adult, teacher or local pharmacist for advice on what will grow and is safe to use.