No, these beautiful stones aren't formed from crystallized silicia over millions of years. They were formed in only a few years from layers of paint in old car factories.
The colorful layered objects are called Fordites and take their name from agate stones for their visual resemblance.
While today, cars are painted by way of an electrostatic process that essentially magnetizes the enamels to the car bodies and leaves little or no overspray, back in the old days, automobile paint would drip onto the metal racks that transported cars through the paint shop and into the oven. The paint was hardened to a rock-like state thanks to high heats from the baking process.
As the urban legend goes, plant workers would take pieces home in their lunch pails as a souvenir for their wife or kids.
The modernization of car production has rendered Fordite a relic of the past. Artisans have been using the colorful material for jewelry but it’s not a stretch to imagine a future when these pieces sit behind glass in a museum.
The colors can also be used to judge how old they are because car paint was subject to different trends. In the 1940s cars were mostly black or brown enamel while the 1960s ushered in an age of colorful lacquers.
Via ThisisCollasol, My Modern Met, Fordite.com. Thanks Joris, Arne.