Field of Science

Atomic Bomb Dropped Over Japan Created A New Kind Of Minerals - Hiroshimaites

The nuclear fire above Hiroshima in the early morning of August 6, 1945, not only vaporized parts of the city but also created new minerals. In 2015 geologist Mario Wannier discovered small particles of metal and glass in the sand collected along the shores of Miyajima Island and Motoujina Peninsula, located south of the hypocenter of the explosion.

Hiroshima city and bay area with location of the A-bomb hypocenter and sampling sites at Motoujina Peninsula and Miyajima Island. Optical microscopy image with a collection of glass spherules, cemented fragments and metallic spherules. From WANNIER et al. 2019.

Chemical analysis showed a layered structure of unknown minerals, mostly combinations of aluminum, silica, iron and calcium. The researchers argue that the particles formed by condensation from the mushroom cloud after the nuclear blast. As the mushroom cloud, containing traces of vaporized materials like stone, steel, concrete and rubber, cooled along its borders, small particles of glass-like material formed and rained down. Currents and the movement of the waves later accumulated the particles in the sand along the shores around the hypocenter of the explosion. Based on the unique chemical composition and the site of the discovery, the researcher named the new minerals Hiroshimaites, as they are artificial "tectites" (droplets of molten material formed by the heat of a meteorite impact). The studied sand samples contained up to 2% of particles, so along the shores of Hiroshima estimated 2,000 to 3,000 tons of Hiroshimaites may still lay in the ground.