LED-Embedded Rocks Used to Illuminate ‘Digital Campfire’ – Dutch artist Daan Roosegaarde’s light installation, called Crystal, consists of 700 rocks on a mat.
Each rock … is made out of a unique salt which grows in perfect geometric shapes around two LEDs. These are wirelessly charged via a power mat on the ground. The project’s interactivity is proximity-based. In their dormant state, the crystals appear to “breathe” light, slowly lighting up and then dimming; when visitors start to move and interact with them, their lighting behavior changes.