Scientists Discover Atomic-Forged Glass on Hiroshima's Beaches

Hiroshima's beaches are covered in nuclear fallout debris.
May 13, 2019, 5:28pm
Hiroshimaites. ​Image: UC Berkeley
Hiroshimaites. Image: UC Berkeley

Tiny aerodynamic glass particles found on the beaches of Hiroshima were likely formed in the fires of an atomic blast, says a new study.

According to the study, published in Anthropocene on Monday, the particles could only have been forged in extreme heats above 3,300 degrees Fahrenheit. "Little Boy"—the Bomb America dropped on Hiroshima on August 6, 1945—vaporized the city, unleashed a fireball that reached 17 million degrees Fahrenheit.


Retired geologist Mario Wannier was sifting through the sand on a beach on Japan's Motoujina Peninsula when he noticed the strange glass. Wannier's trained eye can identify various minerals in a bucket of sand at sight—but the small glass beads he found puzzled him. "They are generally aerodynamic, glassy, rounded—these particles immediately reminded me of some [rounded] particles I had seen in sediment samples from the Cretaceous-Tertiary boundary," Wannier said in an interview with UC Berkeley.

Wannier and a team of researchers from UC Berkeley studied the glass and discovered that the silicon forming the glass was full of odd materials not normally seen in sediment. Some samples were mostly made up of just oxygen and carbon, but others provided a wide variety of different materials, including aluminum, calcium, silicon, chromium rich in iron, and crystalline structures.

Even stranger was the presence of anorthite and mullite crystals, rare earth minerals usually seen around meteorite impact sites and volcanoes. Anorthite is typically formed from cooling lava, and mullite is created when silicon is blasted with heavy heat. Such minerals, it seems, only occur in the event of catastrophic destruction.

Hiroshima's atomic blast created the perfect conditions to create these strange minerals. Many of the materials found in the minerals—rubber, stainless steel, concrete, and marble—were common in Hiroshima at the time of the bombing.

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Researchers theorized that the physical matter of the city surged into the air, formed with particles from the ground at a high elevation, and rained down as glass. Cooling in the descent, these minerals formed the aerodynamic shapes of the "Hiroshimaites"—rare minerals unique to the beaches of Japan. They occur nowhere else on the planet.

"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." Wannier said.