Here’s a fun experiment you can try at home to make miniature cold lightning using rocks from your yard, or candy.

First, look for some quartz pebbles. Preferably milky white ones.

Next, find some wintergreen Life Savers—or white sugar candies will do.

Then grab some safety glasses, because you’ll be smashing things.

Now go to a darkened room, let your eyes adjust, and rub the pebbles together. Try different levels of friction and speed. You should see a flash of light in one or both pebbles as friction causes them to luminesce—without producing a spark.

This is called triboluminescence, which happens when some materials rub together or break.

Now try crushing the Life Savers with a hammer or pair of pliers. The wintergreen oil will also fluoresce, increasing the effect.

Scientists are still not exactly sure how this happens. It’s thought that the friction or cracking causes positive and negative charges to separate. When they recombine in the presence of nitrogen in the air, they produce cold light, without heat, similar to lightning in a cloud.

Besides being a neat trick, researchers are trying to put it to use. They’re experimenting with integrating triboluminescent materials into high-value items, like bridge structures or spacecraft parts.

Using special sensors that can see the faintest luminescence, they hope to observe fractures developing before critical failures could occur. A cool benefit from cold lightning.