Molly's Crystal Growing

See how the magic works

Initial Research - Thursday 12th September

Crystals are solids that form by a regular repeated pattern of molecules connecting together. In crystals, the Unit Cell is repeated in the same arrangement over and over throughout the whole crystal.

Crystals can be made from many things. The crystals we will make are made with potash alum and hot water. They can also be made at home using things like sugar, salt and water.

Crystals in nature include diamonds, snowflakes and salt. Some these types of crystals are used for jewellery and can be very valuble. Household crystals are things like sugar and salt.

Crystals often form in nature when a liquid will cool down and begin to harden. Particular molecules in the liquid join together as they try to become stable. This happens in a repeating pattern that forms a often structured crystal.To grow a crystal, things work differently. This is called nucleation. The molecules of the solute and solvent attempt to stick together, despite other forces in the solution trying to keep them apart. Every so often, a solute and solvent will stay together long enough to attract another molecule and so on until a crystal begins to form.

Crystals can grow in different shapes and sizes depending on the internal symmetry of the crystal, relative growth rates, conditions and the different atoms and molecules change the shape also.

The ideal conditions for crystal growth are;

-Supersaturated solution
- Porous material as crystal foundation
- Warm air temperature to speed growth
- Sufficient light

  • Tetragonal - Shaped with two identical squares and four identical rectangles.
  • Isometric - This shape is made up of six, two-dimensional squares. All sides are equal
  • Hexagonal - An eight sided figure. Six identical rectangles and two hexagons.
  • Orthorhombic - Three different rectangles. Opposite sides are identical.
  • Monoclinic - Has one angle that is not a right angle.
  • Triclinic - No right angles. All sides are different.

MSDS Sheet


Session 1 - Tuesday

  • Materials
    • 2 250ml beakers
    • Filter Funnel
    • Filter paper
    • Hot water
    • 25g potash alum
    • Stirring rod
    • Place 25g of potash alum in a beaker (250ml or bigger.)
    • Add 170ml of hot water.
    • Stir the mixture until all the crystals have dissolved.
    • Pass the solution through a filter funnel (with filter paper) into a clean beaker.
    • Cover the beaker with a watch glass or another piece of filter paper.
    • Leave solution in a cool sheltered place overnight.

Everything seemed to go according to plan when making the crystals at this stage. The potash alum took a while to dissolve and the filtering took a long time. We covered the solution with a watchglass and left it overnight.

Session 2 - Wednesday

  • Overnight the bottom of the beaker should have become covered with a small layer of crystals. If the are no crystals on the bottom, follow the steps below. If there are crystals, move onto session 3.
    • Add one potash alum crystal to the mixture.
    • Cover and leave overnight.
  • OR:
    • Scratch the bottom of the beaker with a glass stirring rod.
    • Cover and leave overnight.

Overnight, our solution had formed lots of very small crystals. They looked almost like sand although they were clear. We carefulled scraped them off the bottom and left them overnight once more.

Session 3 - Thursday

  • Materials
    • 2 250ml beakers
    • Tweezers
    • Ruler
    • Camera
    • Overnight, the bottom should have become covered with a layer of small crystals.
    • Carefully pour the liquid that remains in the beaker into a clean beaker.
    • From the crystals at the bottom of the beaker choose one good symmetrical crystal to be used as a 'seed' for a big crystal.
    • Remove this crystal from the beaker and put it into the other beaker. Try to put it into the middle.
    • Take a picture of the crystal next to a ruler and mark the height of the liquid on the beaker. Record the date.
    • Cover the beaker with paper and put it in a safe spot that isn't in direct sunlight or near a heater.

The next day, our crystals had not changed much but the small crystals did clump together in some cases. I transfered mine to a jar and poured on about 1.5cm of the solution. At home, I put it on a shelf in a dark, cool room and covered it with newspaper.

Crystals Activity Sheet

1 week after - observations

My crystals have not grown over the week and the same amount of the solution remains. The only change I can see are the small grey/black things floating in it. I think that this might be ink from the newspaper I covered it but I'm not sure.

2 weeks after - observations

Even after 2 weeks, my crystals have not grown. They still have the same amout of solution too. The small grey dots have not gone away. The jar has been kept in exactly the same conditions as the week before.

Finished Crystals!

In the last week of growing my crystals, I decided to try a different approach, as nothing was happening, and I placed them under a lamp for about a day. I think my crystals grew slightly and some of the solution was gone.

My crystals came out looking quite good and were a reasonable size. They looked like sheets of tiny crystals stuck together

Overall in my crystal growing, I don't think too much of the method worked out correctly. They did not form correctly overnight, the solution did not dissapear and the crystals didn't grow much. If I were to make them again I would probably change the conditions that they were in and see if it produced better crystals. I also would suspend them in the solution for better growing.

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