It was 1984 when farmer Margrit Christen near Nidau, just north of the Lake of Biel, Switzerland, after ploughing found a peculiar looking stone. It was the first and still largest mass of the Twannberg Iron IIG Meteorite (TW1, 15.9kg).
The Twannberg meteorite is chemically a rare IIG iron and structurally a hexahedrite. These meteorite is one of only six Hexahedrit IIG iron meteorites found on earth. With the classification of Twannberg in 1986 and Guanaco in 2001. These meteorite are hexahedrites being very low in nickel (4.1 to 4.9% Ni in metal) and high in P, leading to characteristic large inclusions of skeletal schreibersite (Fe,Ni)3P.
Ongoing scientific research shows that the Twannberg meteorite fell 200,000 years ago (+/- 20,000 years). Some pieces even showed delicate flowlines and original fusion crust.
Observed fall: No
Year found: 1984
Country: Twannberg, Canton of Berne, Switzerland
Classification history: Iron, IIG
Dimension: ~ 80x67x32mm
Meteoritical Bulletin Database: https://www.lpi.usra.edu/meteor/metbull.php?code=24088