This experiment is for advanced students. Water Glass is another name for Sodium Silicate (Na2SiO3), which is one of the chemicals used to grow underwater rock crystal gardens. Metal refers to the metal salt seed crystal you will use to start your crystals growing. You can use any of the following metals listed. Note however, that certain metals will give you different colors of crystals.
Your crystals begin growing the instant you toss in the seed crystals. These crystals are especially delicate and fragile – just sloshing the liquid around is enough to break the crystal spikes, so place your solution in a safe location before adding your seed crystals.
After your garden has finished growing to the height and width you want, simply pour out the sodium silicate solution and replace with fresh water (or no water at all). Due do the nature of these chemicals, keep out of reach of small children, and build your garden with adult supervision.
Here’s what you need to get:
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- Clean glass jar
- Sodium silicate (check shopping list for online ordering)
- One (or more) of the following for different colors:
- White – calcium chloride (found on the laundry aisle of some stores)
- Purple – manganese (II) chloride
- Blue – copper (II) sulfate (common chemistry lab chemical, also used for aquaria and as an algicide for pools)
- Red – cobalt (II) chloride
- Orange – iron (III) chloride
Download worksheet and exercises
The seed crystals are metal salts that react with the water/sodium silicate solution to climb upwards in the solution, as the products are less dense than the surrounding solution.
Troubleshooting: If you add too many seed crystals, your solution will turn cloudy and you’ll need to start all over again! Add your seed crystals sparingly – you can always add more later.
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