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What You Need to Know about Growing Crystals

Crystals that you can grow at home are grown from solutions in water. To grow a crystal, you dissolve a chemical in water, then either evaporate the water or cool the solution so that the substance starts to crystallize. Usually you hang a string or a seed crystal in the growing solution to provide a surface for the crystals to form. You want water to be able to evaporate from the solution, so you can't seal the container. However, you can place a coffee filter or paper towel over your solution to keep it clean. Crystals grow best if they are undisturbed. You can watch them grow, but don't pick up the container or shake it.

Sorry, only Mother Nature can grow the crystals like the ones in the picture to the right. To learn more about them, click on that image. There are however many types of crystals that you can grow, including some that come from foods. Even young children can grow these crystals. The crystal solutions start out very hot, however, so adult supervision is important.

There are even some tricks you can do to control the shapes and colors of the crystals you want. Have fun!

Solutions to Common Crystal Growing Problems

When Crystals Won't Grow

There are three main problems you may encounter with your crystals.


If you have an impurity (e.g., dishes weren't quite clean, chemicals weren't pure, or possibly you made a mistake with a chemical), your crystals may not grow or else they might not look like you had expected. There isn't much you can do to fix this problem except to start over, but before you do, eliminate the other main causes of problems.

Solution Not Saturated

Usually crystals don't grow because there wasn't enough crystal material dissolved in the water. You can concentrate an existing solution by increasing the rate of evaporation of the solution. The best way to achieve this is by improving the air circulation around the crystal solution. Placing the solution near a fan would work, for example. Lowering the temperature of the solution may help, too. This doesn't speed evaporation, but sometimes crystals will fall out of solution as it becomes cooler. Try refrigerating your crystals.

Undissolved Material

Another common problem you may encounter is crystals growing on the bottom of the container and not on your string. This occurs when the solution contained undissolved material. One way to lessen the chance of this happening is to filter your solution through a coffee filter or paper towel.

Sugar Crystals or Rock Candy

Turquoise Browed Mot MotWhat you do:

  • 1.Stir 3 cups of sugar into 1 cup of boiling water. Keep stirring until as much sugar has dissolved as possible. You can add food coloring to the solution if you like.

  • 2.Pour the solution into the container you have selected for growing the crystal. Avoid getting any undissolved sugar in this container, since the sugar will provide a growing surface for the crystals, causing them to grow on your container.

  • 3.Suspend a wooden skewer or rough string into the solution.
  • 4.Allow the solution to sit undisturbed.

Salt Crystal Geode

Alum crystal

This is one trick you can use to control the shape of your crystals, make a geode!
What you will need:

•boiling water
•food coloring (if you want colored crystals)
•small bowl or cup

Prepare the Shell
A natural geode forms inside a mineral, in this case the mineral is the calcium carbonate of an eggshell. Carefully crack open an egg, eat the egg, and keep the shell. Clean all of the egg stuff from the shell. Try for a clean break, to create two halves of the shell maybe even try to break it from end to end. If you want a rounded geode you may wish to just remove the top of the shell. This trick can also be used with other types of crystals.

  • 1.Add salt to boiling hot water until no more will dissolve. The temperature is important, since much more salt will dissolve with even a couple degrees hotter water.
  • 2.Find a bowl or cup that is just a little larger than your eggshell. Boil enough salt solution to fill this container.
  • 3.For larger crystals, you need a seed crystal. Get a seed crystal by pouring a small amount of this solution onto a saucer. Let the liquid evaporate. Carefully scrape the best crystal from the saucer and attach it to a nylon line
  • 4.Add food coloring if colored crystals are desired.
  • 5.The best salt crystals take several days to weeks to grow. Allow the solution to sit undisturbed in a cool, dry location. Allow the solution to evaporate. Crystals will start to form over the course of a few days. You can remove the geode whenever you are pleased with its appearance and allow it to dry. The largest crystals will result from allowing the solution to fully evaporate, which could take a few weeks, depending on the humidity level in your home.

Alum Crystals

alum crystal

The crystal here is a little more complicated so click on the crystal for the directions to this one.

What you will need:

  • 2 plastic cups
  • alum which is formally called ammonium aluminum sulfate
  • popsicle sticks
  • thread

Copper Sulfate Crystals

Copper Sulfate crystal

What you will need:

  • Copper sulfate (to be used with adult supervision)
  • water
  • jar
  • dirt
  • thread or fishing line

Although beautiful, this chemical IS extremely toxic! Copper sulfate crystals are among the easiest and most beautiful crystals that you can grow. The brilliant blue crystals can be grown relatively quickly and can become quite large. Here's how you can grow copper sulfate crystals yourself.

Make a Saturated Copper Sulfate Solution

Stir copper sulfate into very hot water until no more will dissolve. You can just pour the solution into a jar and wait a few days for crystals to grow, but if you grow a seed crystal, you can get much larger and better-shaped crystals.

Grow a Seed Crystal

Pour a little of the saturated copper sulfate solution into a saucer or shallow dish. Allow it to sit in an undisturbed location for several hours or overnight. Select the best crystal as your 'seed' for growing a large crystal. Scrape the crystal off of the container and tie it to a length of nylon fishing line.

Growing a Large Crystal

  1. Suspend the seed crystal in a clean jar that you have filled with the solution you made earlier. Don't allow any undissolved copper sulfate to spill into the jar. Don't let the seed crystal touch the sides or bottom of the jar.

  2. Place the jar in a location where it won't be disturbed. You can set a coffee filter or paper towel over the top of the container, but allow air circulation so that the liquid can evaporate.

  3. Check the growth of your crystal each day. If you see crystals starting to grow on the bottom, sides, or top of the container then remove the seed crystal and suspend it in a clean jar. Pour the solution into this jar. You don't want 'extra' crystals growing because they will compete with your crystal and will slow its growth.

  4. When you are pleased with your crystal, you can remove it from the solution and allow it to dry.

Tips & Safety

  • Even a small increase in the temperature of the water will greatly affect the amount of copper sulfate (CuS04 . 5H20) that will dissolve.

  • Copper sulfate is harmful if swallowed and can irritate skin and mucous membranes. In case of contact, rinse skin with water. If swallowed, give water and call a physician.

  • Copper sulfate pentahydrate crystals contain water, so if you want to store your finished crystal, keep it in a sealed container. Otherwise water will evaporate from the crystals, leaving them dull and powdery. The gray or greenish powder is the anhydrous form of copper sulfate.

  • Copper sulfate is used in copper plating, blood tests for anemia, in algicides and fungicides, in textile manufacturing, and as a dessicant.

Potassium Ferricyanide Crystals

Copper Sulfate crystal

What You Need

  • 93 g potassium ferricyanide
  • 200 ml warm water
  • clear glass or plastic container
  • coffee filter or paper towel
  • string/pencil (optional)
  • spoon or stirring rod

Don't let the cyanide part scare you. It's a medicine and you may or may not find it in local pharmacies here, most likely you need to get it from a chemical company. Grow red crystals without dye! Potassium ferricyanide (K3Fe(CN)6), also known as 'Red Prussiate of Potash', makes beautiful red monoclinic crystals. Don't be too concerned about the 'cyanide' part of the chemical name. You shouldn't eat your crystals or drink the liquid, but it's safe to grow these crystals on a countertop or pour your waste down the drain.

  • Place 93 grams of potassium ferricyanide and 200 ml warm water into a clear container.
  • Stir to dissolve.
  • If you wish to grow a single large crystal, pour a few drops of this solution onto a saucer or other shallow dish (perhaps with a string laid across the liquid, otherwise tie crystals from the plate onto a string). Allow this liquid to evaporate to form seed crystals. Tie the string to a pencil or butter knife to suspend the string into the original container, being careful not to touch the sides or bottom of the container.
  • Cover the container with a paper towel or coffee filter. You want evaporation to occur, but you don't want contaminants to be able to fall into your crystal-growing solution.
  • Leave your solution undisturbed, but check on it from day to day to watch your crystals grow.
  • Once the crystals have reached the desired size (probably after a week or two), remove the crystal and allow it to dry on a paper towel. Once dry, you can store your crystal wrapped in a piece of tissue.
  • Alternatively, you could allow all of the liquid to evaporate from the container (takes about a month, depending on ambient temperature and humidity).
  • Tips:

      If you are having trouble getting all of the solid to dissolve, try using hotter water. If the solid still won't dissolve, allow the solution to settle out, then use only the clear portion for growing crystals (decant it or carefully pour it the solution into a clean container). If you have solids in your starting solution, the crystals will form (nucleate) around the particles and the resulting crystals will be smaller than if you used a clear solution.

      Bats in Your Belfry

      batHave you seen any of the bats here? Don't be afraid of them because they keep the mosquito population down and will not attack you. Did you know that half of the population of mammal species here in Guatemala belong to bats? There are even some species that you will only find in this area of the world like the Bulldog fishing bat that you may see flying over the water looking for their dinner at night. Each bat can eat thousands of flying insects an hour. We should all be thankful!

      Here's another drawing project for you. Click here for a "connect-the-dots" bat. To print the image, right click on it and select "print..." If you would like t learn more about some of the bats around here and why you don't need to be afraid of them, click here.

      Who Ate Waldo?

      The rainforest is a beautiful place. It is also a place to respect and understand that it should be entered only when you know how to be safe. If you do not know the different kinds of things that can hurt you, there is a bigger chance that you won't even see the danger until it is too late. Many animals, reptiles and even insects look much like the areas of the forest that they live in. There are also many of them that protect their homes from predators that may threaten their sources for food and habitat with a bite or painful sting. Below is a sample of how some animals and insects hide in plain sight.

    Leaf Tailed Gecko
    Leaf Tailed Gecko
    Walking Stick
    Walking Stick
    Keel Billed Toucan
    Cattle Egret
    Bad Snake
    Great Kiskadee

    Next are some pages that show a typical rainforest full of animals. Your mission should you decide to accept it is to count how many animals you can see. Sorry, there are no of traces of Waldo anywhere.

    Follow this link to page one, and if you got lucky and walked away, you can try page two. If you would like to learn about some of the bugs you should be careful of around here click here.

    Coffee Break

    While you are looking for things maybe you could help me find a friend. Coffee grows here in Guatemala and he went out looking for the freshest cup the last time I saw my friend he was counting these. Maybe you can find him, I know he is there because he couldn't have gone far.