When you add a spoonful of sugar to a cup of tea or coffee, you usually stir it
to help it dissolve. There are two ways of helping something dissolve in a solution:
stirring it and heating it up. But even if you do both of these, there is still a limit to
the amount of sugar you can add to your drink. Eventually you'll reach a stage where no
more sugar will dissolve no matter what you do: your drink is now saturated.
When you grow crystals, you need a saturated solution or the seed crystal will
just dissolve the moment you add it to the solution in the jar. Rather than growing
crystals, you'll be dissolving them. Read the recipe for Alum Crystals and you should understand this
Seed crystals are formed as the water in the saucer evaporates. The tiny
particles of chemical in the solution gradually join together. The crystal in the jar also
keeps growing as the water evaporates. As the solution gets stronger, the particles
crystallise around the seed crystal.
Growing Crystals: recipes
Here's how to grow crystals from Alum, but the method is the same whatever you want to
grow crystals from.
You can buy alum powder from a chemist's shop and growing the crystal will take
about 3 weeks. Pour 600ml (1 pint) of water into a saucepan. Add 100g (4oz) of alum
powder. Gently heat the mixture and stir it to dissolve the powder. Then add as much alum
powder as you can until no more will dissolve.
Let the mixture cool, then pour some into a saucer and stand it somewhere cool.
Pour the rest of the solution into a glass jar. Stir an extra tablespoon of alum into the
jar to make a saturated solution. Cover the jar with a cloth. After a few days, small
crystals should start to grow in the saucer. Leave them until all the solution has
evaporated then choose the biggest as your seed.
Carefully tie a long thread around the seed crystal and wind the other end
around a pencil. Hang the crystal in the solution by balancing the pencil across the jar.
Put the jar somewhere warm like the airing cupboard. The crystal should grow for about two
weeks. When it stops growing, take it out of the jar and wrap it in a piece of tissue.
Once you've grown more crystals of different sizes and colours use something
other than alum you can arrange them in a display.
Also known as "Red Prussiate of Potash" and has the chemical formula
of K3 Fe(CN)6. This recipe gives red monoclinic crystals.
Dissolve 93 grams of potassium ferricyanide in 200ml of warm water, cover the
solution, and allow it to cool. Do not be especially afraid of the word
"cyanide" in the name; this substance is no more poisonous (and no less!) than
the others in the list.
Copper Acetate Monohydrate
Chemical formula: Cu(CH3COO)2.H2O. This recipe
gives blue-green monoclinic crystals.
Dissolve 20 grams of copper acetate monohydrate in 200ml of hot water. If a scum
of undissolved material persists, add a few drops of acetic acid and stir well. Cover this
solution, and allow it to cool and stand for a few days; usually it will deposit crystals
Calcium Copper Acetate Hexahydrate
Chemical Formula: CaCu(CH3COO)2.6H2O. This
recipe gives blue, tetragonal crystals.
Add 22.5 grams of powdered calcium oxide to 200ml of water, pour into the
mixture 48 grams of glacial acetic acid, and stir until the solution is clear. If there is
a small insoluble residue, filter the solution. Dissolve separately 20 grams of copper
acetate monohydrate in 150ml of hot water. Mix the two solutions, cover the mixture, allow
it to cool for a day. If it does not deposit crystals spontaneously, let a drop of the
solution evaporate and scrape the resulting seeds into the bulk of the solution.
More Recipes for Crystal
5 tbsp. Salt
5 tbsp. Epsom Salts
6 tbsp. hot Water
5 tbsp. hot
6 tbsp. Water
Green food coloring
Blue food coloring
You will need eight clear plastic beverage cups. With a permanent
marker, label each one. Stir until most of the salt or sugar dissolves. Then scoop out one
teaspoon of the liquid from each cup and place it in another set of cups that are labeled
like the first set.
This second set will evaporate more rapidly and crystals will be smaller in
size. Keep a magnifying glass by the "growing" garden so that you can observe
the crystals as they form. If you can get a microscope, put some crystals on a glass slide
for viewing. It will probably take up to a month for all of the liquid to evaporate, but
you will be rewarded with good-sized crystals for your efforts.
Growing Crystals (True Books)
Crystals and Crystal Growing
Discovery Exclusive Crystal Growing Kit
Scientific Explorer's Jiggly Gems & Crystal Growing Science Kit