How To Grow Red Potassium Ferricyanide Crystals

Potassium ferricyanide is also called Red Prussiate of Potash.
Potassium ferricyanide is also called Red Prussiate of Potash. It forms red monoclinic crystals. Ben Mills

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.

Difficulty: Average

Time Required: one or more weeks

Here's How:

  1. Place 93 grams of potassium ferricyanide and 200 ml warm water into a clear container.
  2. Stir to dissolve.
  3. 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.
  4. 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.
  5. Leave your solution undisturbed, but check on it from day to day to watch your crystals grow.
  6. 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.
  1. Alternatively, you could allow all of the liquid to evaporate from the container (takes about a month, depending on ambient temperature and humidity).


  1. 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.

    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