How to Grow a Giant Crystal from Copper Sulfate

Copper sulfate crystals are probably among one of the prettiest crystals you can grow at home, with even just a simple setup with some copper scrap and vinegar already capable of producing lots of them. Yet what if you want to grow really big ones? In that case the [Crystalverse] has got your back, with a recent video that expands on an older blog post.

In lieu of the copper-and-vinegar approach you can also obtain copper sulfate directly, since it’s a common fungicide, rootkiller as well as drying agent. This means that your local brick-and-mortar retailer or favorite online store probably has a few kg of the stuff available for sale.

As with most large crystal growing procedures the key is to have a saturated solution, which for copper sulfate just takes near-boiling water, to create a mesmerizingly blue liquid if there are no contaminants in it. By adding slightly more copper sulfate there are also crystallization sites on the bottom of the jar to draw these away from your large crystal.

From there it’s the same as with growing other large crystals – even those from sugar – with a seed crystal suspended into the solution, along with a silent prayer to the crystal gods that said seed crystal continues to grow without any defects. One gotcha with copper sulfate crystals is that the intense blue color is largely due to the presence of water molecules. This means that once it dehydrates, it turns effectively white.

Also of note that is the slower the crystal grows, the better the result is likely to be. During the months that it takes for these large crystals to grow, you need to carefully manage the copper sulfate solution, remove competing crystals on the bottom of the container and keep the temperature as constant as possible.