Agate gemstones are known for their amorphous, fluid patterns and colors created by the slow accumulation of sedimentary layers. But in the case of the obscure “gems” known as “motor agate” or “fordite,” instead of sediment and minerals, the layers are made of car paint.
Pieces of fordite certainly look as though they could have been fashioned deep within some colorful part of the Earth. Largely, though, fordite was created well above ground in the auto plants of Detroit, Michigan.
Beginning in the 1930s and 1940s, American automobiles began being painted via spray techniques that produced large nuggets of excess paint, built up in layer after layer of color. When the cars’ coating would be heated to harden, these overspray deposits would harden right along with them, bringing them to an almost stone-like hardness. A 2013 article about fordite in The New York Times refers to this excess as “enamel slag.”
Once these globs were sufficiently large enough to get in the way of the factory line, they would be broken off the bars and skids they were hanging from, and generally tossed away as waste. “Most of the good stuff is already buried in landfills,” says Cindy Dempsey, an independent jewelry creator and owner of Urban Relic Design, who has been working with motor agate for over 20 years.