Happy National Fossil Day!
The process of petrification, or fossilization, begins when a dead plant or animal is buried in sediment. Over time, sediment builds up, and the weight of the sediment turns it into sedimentary rock. During this process, groundwater seeps into the organism’s remains, leaving behind minerals that create the fossil. In some cases, groundwater contains uranium, which comes from the weathering of some rocks. Organic material like the dead organism creates perfect conditions for uranium to settle, creating radioactive fossils.
Uranium mining has uncovered many of these fossils. The Chinle Formation in southeastern Utah is rich in fossils, including fish and early dinosaurs. This area is also the site of small uranium mines, which typically extract ore from the clay deposits in this area. Clay deposits are a remnant of prehistoric forests, which often bear fossils.
Some of these radioactive fossil specimens have found their way to museums, where they may be coated in lead paint to reduce radiation exposure. The main concern around these fossils is dust from excavation and cutting, which is harmful when inhaled. Some museums and collections even have cabinets that are monitored for radon gas, which is a byproduct of uranium decay.
