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Introduction To Crystal Growing
In this kit, we show you how to make crystals of different shapes, sizes, and colours.
By experimenting and developing the basic methods, you can create a range of
beautiful crystals. However, before we begin, we need to explain what crystals are.
Millions of years ago, the Earth was not as we know it now, but a mass of constantly
moving hot gases. At some point in time, the gases cooled and formed liquids, some
of which cooled further to become solid materials.
Crystals are solid materials with atoms or molecules that are arranged in orderly,
repeating patterns extending in all three dimensions. Non-crystalline (or amorphous)
materials don’t have this orderly structure. A fundamental property of crystals is their
geometric symmetry. There are 6 different symmetrical shapes used to classify
crystals:
• Cubic – all sides are equal and at right angles to one another
• Tetragonal – this is a cube that has been stretched in one dimension,
so the base is square, but the sides are rectangular
• Monoclinic – the base is a parallelogram instead of square, but the sides
are rectangular
• Triclinic – both the sides and base are formed from parallelograms
• Hexagonal – the base is a hexagon and the sides are rectangular
• Orthombic – similar to a cubic lattice, but one that has been stretched
in two dimensions, so the length, width and height are all different
Our kit uses two types of chemicals for growing chemicals: monoammonium
phosphate, which forms tetragonal crystals, and aluminium potassium sulphate,
which forms monoclinic crystals.
ACTIVITY 1 – Ice Crystals
ACTIVITY 2 – Other Common Crystals
You will need:
• Petri dish
• Water
Method:
Pour a small amount of water into the petri dish and place this in the freezer compartment
of a fridge/freezer. Check regularly for the formation of ice crystals in the dish. Look
closely with your magnifying glass – they should look just like snowflakes!
We’ve included a table on page 12 that you can use to record the results
of your experiments. Doing this is a good way of remembering the
experiments that worked well, or those that didn’t, and the reasons why.
You will need:
• Table salt
• Epsom salts
• Clean jam jar
• Pencil
• Paper clip
• Cotton thread
Recipes for salt solutions:
Table salt: 5 tablespoons of salt to 6 tablespoons of water
Epsom salts: 5 tablespoons of Espsom salts to 6 tablespoons of water
Method:
Use a jam jar to prepare one of the two solutions. Add the correct amount of hot water
from the tap to the jar, and then gradually add the table salt or Epsom salts. Add the salt
etc. gradually, stirring well each time, and waiting until it has disappeared before adding
more. Keep adding it until it is not possible to dissolve any more salt in the water, and
there is a small amount left in the bottom of the jar. You have made a saturated solution,
from which you can grow crystals.
Take the pencil and tie a piece of cotton to it, and then attach a paper clip to the free end
of the cotton to hold it down in the solution. Balance the pencil on the rim of the jam jar
with the paper clip immersed in the solution
and cover. Allow to cool and leave
undisturbed for a day or two. Watch
the formation of crystals on the cotton
and check the shape of the crystals
with your magnifying glass.
Tetragonal
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Isometric
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Monoclinic
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Triclinic
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Hexagonal
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Orthombic
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Please note: drawings underneath show the shape of the base of the crystals.
Salt crystals growing on string
