Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Meteorites from inner Solar System match up to Earth's plantinum standard

Some of the world’s rarest and most precious metals, including platinum and iridium, could owe their presence in the Earth’s crust to iron and stony-iron meteorites, fragments of a large number of asteroids that underwent significant geological processing in the early Solar System.

Dr Gerhard Schmidt from the University of Mainz, Germany, has calculated that about 160 metallic asteroids of about 20 kilometres in diameter would be sufficient to provide the concentrations of these metals, known as Highly Siderophile Elements (HSE), found in the Earth’s crust. Dr Schmidt will be presenting his findings at the European Planetary Science Congress in Münster on Monday 22nd September.

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.”

During a 12-year study, Dr Schmidt and colleagues have analysed the concentrations of HSE at meteorite impact sites around the world, as well as in the samples from the Earth’s mantle and crust. In addition, he has compared the data from the Earth with data from impact breccias from the Moon brought by the Apollo missions and Martian meteorites, believed to be samples from the mantle and crust on Mars.

Although HSE were present in the nebula from which the Earth formed, as the young planet evolved and heated up they were stripped, along with other heavy elements, from the silicate mantle into the iron and nickel-rich metallic core. The presence of HSE in the mantle is still a matter of debate. However, a widely accepted theory is that HSE were added by meteorite impacts as a veneer of material over the Earth’s surface after the core had formed, about 20-30 million years after the planet’s accretion. This could have been by the collision with a Mars-sized impactor that led to the formation of the Moon. Different classes of meteorites have characteristic elemental ratios of HSE that give indications where in the Solar System they formed. However, the characteristic ratios of HSEs in the Earth’s upper mantle (for example the ruthenium/iridium element ratio of about 2) match up with theoretical predictions for asteroids formed in the Mercury-Venus region.

The Earth is a differentiated body, with a iron-nickel core, a silicate mantle, and evolved silicate crust. Dr Schmidt’s study shows that the abundance ratios of HSE in the Earth’s crust are much higher than those found in stony meteorites, known as chondrites, which represent the pristine material from the early Solar System. The ratios of HSE found in the crust bear a much closer resemblance to iron or stony-iron meteorites. These are fragments of larger asteroids that have had enough internal heat in the past to form a molten metal core. The HSE concentrate preferentially in the liquid core and at the boundary with the solid, rocky envelope. However, the exact ratios of the different metals depend on the physical conditions under which they were formed.

The ratios of HSE found in the Earth’s upper mantle do not exactly match any specimens of meteorites found in collections around the world. Close to the mantle highly siderophile element ratios are data from the iron meteorite Charlotte.

To date, about 20 iron meteorites and about 20 stony meteorites, called chondrites, have been identified as projectiles of the 175 known impact craters on Earth. The projectiles for the other 135 impact craters on Earth are still unknown. No meteorites have been identified as being formed in the region between Mercury and Venus.

Intriguingly, some of the Martian meteorites which are probably most representative of the Martian crust also have HSE values that resemble groups of iron meteorites and stony irons, suggesting that a similar process took place on Mars.

Dr Schmidt said “The first meteorite to be found on Mars was an iron meteorite, discovered by the Opportunity rover in January 2005. Analysis of the Nahkla, Shergotty and Zagami Martian meteorites strongly supports a genetic link with certain iron meteorites and pallasites.”


Highly Siderophile Elements (HSE)
Siderophile (iron-loving) elements are a group of high-density transition metals that tend to bond with metallic iron in the solid or molten state. The HSE group includes rhenium (Re), osmium Os), iridium (Ir), ruthenium (Ru), rhodium (Rh), platinum (Pt), palladium (Pd) and gold (Au).
EPSC 2008 is organised by Europlanet, the European Planetology Network in association with the European Geosciences Union and the Westfälische Wilhelms Universität, Münster.
For further details, see the meeting website:
EuroPlaNet co-ordinates activities in Planetary Sciences in order to achieve a long-term integration of this discipline in Europe.
The objectives are to:
1) increase the productivity of planetary projects with European investment, with emphasis on major planetary exploration missions;
2) initiate a long-term integration of the European planetary science community;
3) improve European scientific competitiveness, develop and spread expertise in this research area;

4) improve public understanding of planetary environments.

Europlanet Project website:
Europlanet Outreach website:
Information films on Europlanet can be found at:
Iron meteorite on the surface of Mars, as imaged by the Mars Exploration Rover Opportunity

Artist’s impression of the metallic asteroid, Kleopatra
Artist’s impression of asteroid impact with early Earth that led to lunar formation

Anita Heward | alfa
Further information:

More articles from Physics and Astronomy:

nachricht Finding the lightest superdeformed triaxial atomic nucleus
20.10.2016 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences

nachricht Innovative technique for shaping light could solve bandwidth crunch
20.10.2016 | The Optical Society

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Innovative technique for shaping light could solve bandwidth crunch

20.10.2016 | Physics and Astronomy

Finding the lightest superdeformed triaxial atomic nucleus

20.10.2016 | Physics and Astronomy

NASA's MAVEN mission observes ups and downs of water escape from Mars

20.10.2016 | Physics and Astronomy

More VideoLinks >>>