If you take a close look at the beaches of Motoujina Peninsula in Japan, you’ll find the sand is littered with tiny glass beads strangely shaped like teardrops as if they’ve been blasted down from the skies.
It might come as no surprise that these unusual objects are the relics of the atomic bombs dropped on Japan in the dying days of World War Two. As reported in the journal Anthropocene, these pieces of debris – dubbed "Hiroshimaites" – are essentially the remains of the city that were blasted into the skies, cooked in an atomic cloud, and later rained down.
While sifting through the sands of Hiroshima Bay and Miyajima Island, geologist Mario Wannier started to notice these glassy flecks and set out on a journey to discover how exactly they were created. In the samples of sand he and his team collected, they found the spheroids and other unusual particles accounted for up to 2.5 percent of all of the grains.
Although most unusual, the teeny structures did remind Wannier of other sediment samples he had analyzed that date to the Cretaceous-Paleogene boundary, better known as that time an asteroid wiped out the dinosaurs 66 million ago. Whatever forged the structures, it must have been an unbelievably epic amount of energy – and since they were found just miles outside the epicenter of nuclear explosions that occurred just 74 years ago, the source of that energy was obvious.
On the morning of August 6, 1945, the US dropped “Little Boy” on the city of Hiroshima, marking just the second ever detonation of an A-bomb and the first nuclear weapon ever used in warfare. Over 70 percent of the city was destroyed in the blink of an eye, along with at least 70,000 people who died instantly. An estimated 200,000+ more died in the following years due to injuries and radiation.
“This was the worst manmade event ever, by far,” Wannier said in a statement. “In the surprise of finding these particles, the big question for me was: You have a city, and a minute later you have no city. There was the question of: ‘Where is the city – where is the material?’ It is a trove to have discovered these particles. It is an incredible story."
A deeper analysis of the Hiroshimaites showed a wide variety in the chemical composition, including concentrations of aluminum, silicon, and calcium. However, some were composed purely of just iron and steel, or even concrete, marble, stainless steel, and rubber.
"Some of these look similar to what we have from meteorite impacts, but the composition is quite different,” explained co-author Rudy Wenk, a professor of mineralogy at UC Berkeley. “There were quite unusual shapes. There was some pure iron and steel. Some of these had the composition of building materials.”
Understandably, the research team concluded that only an atomic explosion could have kicked up such a strange composition.
Next, the team hopes their research will encourage further tests on the samples to see if any samples carry radioactive elements. They'd also like to travel to Nagasaki, the Japanese city hit by the US's Fat Man atomic bomb three days later, to see if similar structures can be found.