Gold, precious forever but especially lately, is a tricky metal. Bound up in consumer electronics, jewelry and the ores that it comes from, gold is difficult to extract, and most modern processes do it with a highly toxic combination of cyanide salts. The cyanide leaches the gold out, but the cyanide can seep into the ground, causing environmental problems and posing threats to human health.

Researchers at Northwestern University recently stumbled upon a solution that uses cornstarch instead. It involves some complex chemistry, but it’s cheap, biologically friendly and nasty-ingredient-free.

Led by Sir Fraser Stoddart, a chemistry professor at Northwestern, the team discovered this method by accident when looking for something else. A postdoc named Zhichang Liu was trying to make three-dimensional cubes out of gold and starch, aiming to use them as storage containers for gases and small molecules.