Nördlingen (Germany): Upon first glance, Nördlingen has all the hallmarks of a classic German town. At its epicenter sits St.-Georgs-Kirche, a medieval church with an imposing tower that dominates the skyline, which itself is punctuated by the red pitched roofs of hundreds of timberframe homes and shops. But on closer inspection, it’s these very buildings that set Nördlingen apart from other towns, and for one very curious reason: These structures are embedded with millions of microscopic diamonds, reports smithsonian.com.
The diamonds are the result of an asteroid, which struck this area of Bavaria, a federal state in southern Germany, some 15 million years ago. The resulting impact left behind the Nördlingen Ries (or Ries crater), a massive depression that stretches more than nine miles across the German countryside, and is the site upon which Nördlingen sits today. The impact also created suevite—an impact breccia or course-grained rock comprised of angular fragments that can include glass, crystal and diamonds, and is commonly found at impact sites such as this one.
When the asteroid hit the Earth, the force caused graphite-bearing gneiss rocks in the region to form diamonds due to the immense pressure—believed to have been 60 GPa, according to one study.
“We assume that the asteroid was a stony one with a weight of [approximately] three billion tons,” says Gisela Pösges, a geologist and deputy director of the Ries Crater Museum in Nördlingen. “[We think that] the asteroid was a similar size to the town of Nördlingen, about one kilometer (less than three-quarters of a mile) across.”