The Unter-Mässing meteorite is currently the largest surviving meteorite in Germany and also the only iron-nickel meteorite in Bavaria. It weighs almost 80 kg (or 2,800 ounces) and, in addition to iron and nickel, it contains small amounts of the rare elements cobalt, germanium, gallium and iridium. That composition is typical of meteorites of this type, while also being a sure sign of their extra-terrestrial origin.
The surface of the meteorite displays the typical shallow indents called regmaglypts that were formed during its passage through the earth's atmosphere.
The substance of this meteorite crystallised four and a half billion years ago, so it originated at the time when our solar system was being formed. As to where it originated – like most meteorites, this one probably started life in the asteroid belt between Mars and Jupiter. Since the iron can only come from the metallic core of an asteroid, it must have been blasted free from one, no doubt during a collision with some other celestial body. Based on geochemical changes to its surface, scientists have established that after being blasted free, the meteorite orbited the sun for another 1.4 billion years before it finally collided with the Earth.
The meteorite was discovered in May 1920 by the brothers Johann and Georg Schäfer from Untermässing near Greding. They were digging out a root of a spruce near their home when they came across a chunk of metal at a depth of about one and a half metres – roughly five feet down. Since they thought it might be valuable, they worked hard to recover it and took it home. Several days went by before the find was identified as a meteorite by a member of the Nuremberg Natural History Society – and saved from being sold to a scrap dealer. The meteorite was officially named "Unter-Mässing" after the place where it was found.
As to the meteorite strike, we can only speculate, and the date of its fall can only be determined indirectly. Remember that it was found in the root system of a spruce. That tree might have been about 120 years old. So the meteorite had probably been in place since around 1800. In fact, a brightly blazing ball of fire was spotted heading south in the sky over Nuremberg in 1807. That may have been when the Untemässingen meteorite fell.