Copper Sulfate Crystals Recipe

blue copper sulfate crystals
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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. 

Grow Copper Sulfate Crystals

  • Copper sulfate crystals are vivid blue diamond-shaped crystals.
  • Copper sulfate crystals are actually crystals of copper sulfate pentahydrate. The compound incorporates water into its structure.
  • The crystals are easy to grow using an inexpensive, common chemical.

Copper Sulfate Crystal Materials

All you need for this project is copper sulfate, water, and a clear container. The chemical is sold as copper sulfate (CuSO4), although it readily picks up water and becomes copper sulfate pentahydrate (CuS04 . 5H20). Buy it as a pure chemical or look for it as the only ingredient in root killer products at home supply stores.

  • Copper sulfate
  • Water
  • Jar

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.

For the best results, grow the crystal in a location with a stable temperature. Temperature fluctuations alternately dissolve the crystal (warm) and deposit crystal (cold). For example, a countertop is a better location than a sunny window sill.

Copper Sulfate Tips & Safety

  • 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.
  • If you choose to handle the crystals, wear gloves. The gloves protect your skin from irritation and also from intense blue staining.
  • 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 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 from efflorescence. 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 desiccant.
  • While municipal water utilities can deal with copper sulfate if you dump it down the drain, take care you don't toss it out into the environment. Copper sulfate is toxic to plants, invertebrates, and algae.


  • Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C., eds. (2003). "Chalcocyanite". Handbook of Mineralogy. Vol. V. Borates, Carbonates, Sulfates. Chantilly, VA, US: Mineralogical Society of America. ISBN 978-0962209741.
  • Clayton, G. D.; Clayton, F. E. (eds.) (1981). Patty's Industrial Hygiene and Toxicology (3rd ed.). Vol. 2, Part 6 Toxicology. NY: John Wiley and Sons. ISBN 0-471-01280-7.
  • Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, FL: CRC Press. ISBN 978-1439855119.
  • Wiberg, Egon; Wiberg, Nils; Holleman, Arnold Frederick (2001). Inorganic Chemistry. Academic Press. ISBN 978-0-12-352651-9.
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Your Citation
Helmenstine, Anne Marie, Ph.D. "Copper Sulfate Crystals Recipe." ThoughtCo, Apr. 5, 2023, Helmenstine, Anne Marie, Ph.D. (2023, April 5). Copper Sulfate Crystals Recipe. Retrieved from Helmenstine, Anne Marie, Ph.D. "Copper Sulfate Crystals Recipe." ThoughtCo. (accessed June 3, 2023).