A leading German scientist has suggested that platinum may have been created in the Earth's upper crust by a series of asteroids colliding with the planet when it was in its infancy.

Dr Gerhard Schmidt, from the University of Mainz, claims that around 160 metallic meteorites with a diameter of 20km hit the Earth after the creation of its core was finalised.

His findings suggest that they provided concentrations of highly siderophile elements (HSEs) such as platinum, iridium, rhodium, ruthenium and palladium, which tend to bond with solid or molten metallic iron.

Dr Schmidt said: "A key issue for understanding the origin of planets is the knowledge of the abundances of HSE in the crust and mantle of the Earth, Mars and the moon.

"We have found remarkably uniform abundance distributions of HSE in our samples of the Earth's upper crust. A comparison of these HSE values with meteorites strongly suggests that they have a cosmochemical source."

Dr Schmidt and colleagues made the discovery after a 12-year study which involved analysing the concentrations of HSE at sites featuring meteorite impacts around the world.

He is set to present his findings at the European Planetary Science Congress, which takes place in Munster this week (22nd-26th September).



Source:

Meteorites could be source of world's precious metals, study finds (22/09/08)
http://cordis.europa.eu/fetch?CALLER=EN_NEWS&ACTION=D&SESSION=&RCN=29890

Meteorites From Inner Solar System Match Up To Earth's Platinum Standard (22/09/08)
http://www.sciencedaily.com/releases/2008/09/080922100455.htm

Cosmic link to precious metals: study (22/09/08)
http://afp.google.com/article/ALeqM5hUnsJNH53XBdgycTIveWq8Vxi7Bw