PREPARATION OF SEED CRYSTALS
Here you will learn how to prepare seed crystals.
The idea is to grow a small perfect crystal around which you will later grow a large crystal.
HERE's WHAT YOU NEED
- Substance to be crystallized
- Distilled or demineralized water
- A shallow dish (e.g., Petri)
- Heating plate or stove
- Fishing line (1 to 2 kg strength)
- A small wood rod (e.g., popsicle stick)
HERE's WHAT YOU NEED TO KNOW
- How much substance you have to work with (weigh on a balance).
- The solubility of the substance in water at room temperature. (Obtain from a chemistry reference book.)
- It would also be useful to know the solubility of the substance at elevated temperatures.
HERE's WHAT YOU DO
- Warm about 50 mL (1/4 cup) of water in a glass container.
- Dissolve a quantity of the substance to produce a saturated solution at the elevated temperature.
- Pour the warm solution into a shallow dish.
- Allow the solution to cool to room temperature.
- After a day or so, small crystals should begin to form.
- Remove some of the crystals.
- With a magnifier select a beautiful and transparent small crystal.
- Tie the seed crystal with the fishing line by using a simple overhand knot.
- Suspend the seed crystal in a shallow (1 to 2 mm deep) small volume (about 1 to 2 ml) saturated solution (for example, in a cover or a Petri dish) for some time (1 to 2 days).
- Check with the magnifier that the seedling crystal is well fixed to the line by its beginning growth. This step is very important because one can lose several days of growth if the "beginning growth" is not regular or not along the structure of the seedling crystal. It is worth checking properly before going on with the regular crystal growth.
Now you are ready to proceed with the preparation of a large single crystal.
Once you have mastered this step, you may be interested in trying to grow single crystals in the presence of
introduced "impurities" that may give different crystal colours or shapes.