A unique World War II battlefield artifact fused to a beach deposit

Intensive military operations took place in the southern Baltic Sea during World War II (WWII). It was also a dumping ground for munitions after the war. During storms, military artifacts are washed onto the coast. The Kołobrzeg beach is a place known for such findings. In Kołobrzeg, one of the most recognizable WWII battles between Polish-Soviet and German troops took place. Here, we report on a unique specimen found on the Kołobrzeg beach in 1996. It consists of three fused components, including conglomeratic sandstone, limestone pebble and a fragment of a worn brass gun bullet casing. Heat markings in the form of a dark halo close to the bullet fragment and black efflorescence on the surface of quartz grains suggest that the fusion was caused by heat during the explosion of gunpowder inside the bullet casing. This process led to the formation of a rock-like material resembling a well-cemented conglomerate.