Grow Copper Sulfate Crystals

Copper sulfate is also spelled copper sulphate, depending on where you live. Both words refer to the same chemical, CuSO4. Other names for copper sulfate are copper(II) sulfate, bluestone, and blue vitriol. This photo (taken by Ben Mills) shows copper sulfate as you would normally see it, which is in its hydrated form, copper sulfate pentahydrate. That's the long-winded way of saying the metal salt has bound to water molecules. This hydrated form is bright blue. If the compound dries up, then it turns a grayish white color.

Why should you care? Because if your copper sulfate crystals get dried out, they will develop a white or gray crust on them, which isn't as pretty as the pure blue color. You can prevent this from happening by keeping your finished crystals sealed up, away from air circulation.

Copper sulfate is used as a fungicide, algicide, and pesticide. It is used to prepare other compounds. It is a component of textile dyes and hair dyes. Copper sulfate burns with a green flame, so it is used to color fireworks and other pyrotechnics.

Copper Sulfate Crystal Materials

You only need two ingredients to grow copper sulfate crystals:

copper sulfate powder
water (distilled is better than tap water)

Make a Saturated Copper Sulfate Solution

The crystals grow from a saturated copper sulfate solution, which means they grow from a solution made by dissolving as much copper sulfate as possible in water. Make a crystal growing solution by dissolving as much copper sulfate as you can in hot water. You want the water to be hot because more copper sulfate dissolves in hot water than cold water. If there is undissolved copper sulfate at the bottom of your container, it's ok! You can pour the saturated solution through a copper filter to separate out the solids. You want to keep the translucent blue liquid.

Grow a Copper Sulfate Seed Crystal

The best crystal specimens are grown from a seed crystal. You can make a seed crystal by pouring a little of your saturated solution into a saucer. Let the liquid evaporate overnight. Scrape the best crystal from the dish. This is your seed crystal.

Grow a Large Single Copper Sulfate Crystal

You can either tie the seed crystal onto a length of nylon fishing line that you suspend into a clean jar that contains your solution or you can set it on the bottom of a clean jar filled with solution. Make sure your seed crystal is fully submerged in the crystal growing solution. Set the jar somewhere quiet since vibrations can slow your crystal growth. It will take several days to a couple of weeks to get a large crystals. When you start to see small crystals growing anywhere in your container except on your seed crystal, remove the seed crystal, put it in a new container, and cover it with the liquid from the jar.

Care for Your Crystal

When your crystal is as big as you want it to get, remove it from the solution and let it dry. You can keep your crystal wrapped in tissue paper or sealed in a bag. Try to keep it away from heat and light, which can dehydrate it and cause it to develop a powdery white coating.