Potassium ferrioxalate crystal

Growing Spectacular Gem-Like Crystals From Rust And Simple Ingredients

When we talk about crystals around here, we’re generally talking about the quartz variety used to make oscillators more stable, or perhaps ruby crystals used to make a laser. We hardly ever talk about homegrown crystals, though, and that’s a shame once you see how easy it is to make beautiful crystals from scratch.

We’ve got to say that we’re impressed by the size and aesthetics of the potassium ferrioxalate crystals [Chase Lean] makes with this recipe, and Zelda fans will no doubt appreciate their resemblance to green rupees. The process starts with rust, or ferric oxide, which can either be purchased or made. [Chase] chose to make his rust by soaking steel wool in a solution of saltwater and peroxide and heating the resulting sludge. A small amount of ferric oxide is added to a solution of oxalic acid, a commonly used cleaning and bleaching agent. Once the rust is dissolved, potassium carbonate is slowly added to the solution, turning it a bright green.

The rest of the process happens more or less naturally, as crystals begin to form in the saturated solution. And boy, did they grow — long, prismatic lime-green crystals, with a beautiful clarity and crisp edges and facets. The crystals don’t last long under light, though — they quickly lose their clarity and become a more opaque green.

[Chase]’s crystal-growing efforts have shown up here before, when he turned humble table salt into beautiful cubic crystals. We find the whole crystal-growing process fascinating, and we’re looking forward to more of this in the future.