The Earth itself was formed 4.5 billion years ago and, at that time, was a molten ball of rack and metal. With iron being heavier than rock, it sank to the center of the planet, where most of it resides today. in the process, it took most of the rare earth metals, including gold and platinum, with it as it sank.
All those resources are far to deep within the Earth for even the most modern of mininig enterprises to reach. In fact, there's such a volume of unreachable rare earth metals in the core that if they were spread over the planet's surface, they would form a layer 4 metres (approx. 12 feet) deep.
Obviously we do have rare metals to work with as evidenced with the gold and other precious metal jewelry that's been produced around the world over the last couple of millennia. So where did that metal come from if all the original rare earth metals sank out of reach into the Earths's core?
We now know that the asteroids are rich in precious and rare metals. So it seemed pretty obvious that after the Earth's crust hardened that there must have been one or more meteorite bombardments that brought those rare metals to Earth, where millions of years later, we could find them and use them to adorn ourselves and in technological devices.
To test this hypothesis, University of Bristol researchers compared the chemical compositions of modern day rocks with 4 billion year-old raocks from Greenland.
They were specifically looking for the rare earth element tungsten - one use we made of tungsten was in the elements imn incandescent light bulbs. To give some idea of its rarity, one gram of rock contains only about one ten-millionth of a gram of tungsten.
Like gold and platinum, tungsten should have sunk into the Earth's core when the planet formed.
As with other elements, tungsten comes in a variety of isotopes - atoms that have the same chemical properties but have different masses. And these isotopes are indicators of where an element originated. Meteoritic tungsten would have a different isotopic signature than tungsten on the early Earth.
The researches identified a difference in the tungsten isotopes in the the modern and ancient Greenland rocks. It may be a small difference but it is significant and backs up the idea that precious rare earth metals arrived in meteorites quite some time after the Earth was born and settled into a stable planet.
There are actually 17 rare earth elements. The etymology of their names, and their main usages is provided here. Some of the rare earths are named after the scientists who discovered or determined their elemental properties, and some after their geographical discovery.
Rare Earth Oxides
The accelerating page of technological innovation has meant we are now using more rare earth metals in high-tech devices than ever before.
Back in 1967, the rare metal Europium was introduced as a source of the color red in TV sets. These days it's used in mobile phones, DVDs, X-Ray machines, MRI scanners and many other devices that we use on a daily basis.
The rise of hybrid cars has seen lanthanum has become a key component of hybrid car batteries. It's now critical to President Obama's campaign to double the fuel efficiency of the American automobile by 2025.
Despite their name, rare earths are not that rare. They're actually as common as lead and copper. However, they are usually found in small quantities which makes them difficult to mine cost-effectively. And there are also some severe environmental hazards associated with them as they are often found along with radioactive materials or other harmful substances.
Alternative energy is becoming more essential as the years pass, to bolster the mainstream energy sources like coal, gas and nuclear as our global demand for energy continues its ever-upward trend. Wind turbines, for example, are one of the fastest-growing sources of emissions-free electricity, and they rely on magnets that use the rare earth element neodymium. And the rare earth element dysprosium is now an essential ingredient in some electric vehicles’ motors.
China has vast rare-earth deposits, mostly in Inner Mongolia, so they're now the biggest producer of rare earths, with more than 95% share of the global market. That could make them as central to rare earth technologies as Saudi Arabia is to oil. China isn't the only only one mining rare earth elements. An Australian company (Australia has some quite large mining interests), Malaysia Lynas & Rare Earths, is now mining rare earth metals in Malaysia. In coming years, we're likely to see other areas of the world being mined for these precious metals as demand continues to soar.
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