Where Does Platinum Come From?

 
How’s this for a science fiction premise: In outer space, humanity finds a precious metal that also cures cancer and solves Earth’s pollution problems.

That’s actually a real-life description of platinum’s use in catalytic converters and as a chemotherapeutic agent to treat some cancers. I didn’t mention that it also speeds up the processing of fossil fuels into everything from gasoline to food wraps.
 

I did mention "precious."

I did mention “precious.”

We didn’t have to go to outer space to find it, though. Platinum came to Earth’s surface in impact events.

What is platinum?

Platinum is a silvery white transition metal found in river deposits. It can also be chemically separated from some nickel and copper ores. It resembles silver, but on the periodic table it’s more closely related to the other rare heavy metals of ruthenium, rhodium, palladium, osmium, and iridium.

Spaniards first saw South American natives making various artifacts with platinum in the 16th century. The conquistadores considered this platina (“little silver”) an impurity in the real treasure they were plundering – silver – but since platina was a little harder than iron, pretty, and unusually heat resistant, they brought some back to Europe.

In 1557, Italian humanist Julius Caesar Scaliger wrote about this strange metal that no furnace could melt. It wasn’t until the 18th century that scientists began investigating and finding uses for platinum and its halides and alloys.
 

Platinum prints, like this 1886 image, used a sheet sensitized with iron and platinum salt solution that was chemically developed to lose the iron and turn the platinum into metal in the exposed areas.

Platinum prints, like this 1886 image, used a sheet sensitized with iron and platinum salt solution that was chemically developed to lose the iron and turn the platinum into metal in the exposed areas.

Platinum has always been rare. Today, some 5 million troy ounces are produced each year.

We use it mostly for jewelry and in catalytic converters. It also is valuable for electrodes, anticancer drugs, oxygen sensors, spark plugs, turbines and as an investment commodity.

The outer space connection

The three major platinum-producing areas today are the Bushveld complex in Africa…
 

The Bushveld Complex is part of the Vredefort Dome.

The Bushveld Complex is part of the Vredefort Dome.


 
Canada’s Sudbury Basin…
 
Sudbury_Wanapitei_WorldWind
 

…and Norilsk, in Russia.
 

The Popigai crater is near Norilsk.

The Popigai impact crater is near Norilsk.


 
Even without knowing that almost all meteorites contain 20,000 to 100,000 times the amount of platinum found in the Earth’s crust, it’s easy to see that a link possibly exists between meteor impacts and platinum deposits.

Indeed, scientists use platinum group abundance (particularly platinum, osmium and iridium) to scout out impact structures in the field today. As you can see above, craters weather away on Earth but these heavy metals stick around, even in small fragments.

So, where in the Universe does platinum come from?

A stellar birth

A young star is made mostly of hydrogen. During its life it forms all the elements between helium and iron through nucleosynthesis.

This process releases more energy than it requires.

When you get into elements like platinum which are heavier than iron, nucleosynthesis requires more energy than it releases. That can’t happen in a regular star, but obviously it has to happen somehow, since these elements exist.

One possibility is that platinum and other heavy elements form and are scattered throughout the universe when a giant red star explodes as supernova.
 

Yes, like all space residents, Earth had its full share of these platinum at first, but very early on this, along with iron and some other heavy minerals, melted and sank down to form the planet’s core. This is why today there is very little platinum at the surface.

Platinum is beautiful, useful and mysterious. You can invest in it, but you also use it every day to reduce your car’s emissions. One day you might even have to pin your hopes on it as a cancer treatment.

We are truly lucky that platinum rained down on Earth from the stars.

Sources:

  • In the Darkroom: An Illustrated Guide to Photographic Processes before the Digital Age. Sarah Kennel. National Gallery of Art. Thames & Hudson. 2009
  • Precious Metals Investing for Dummies. Paul Mladjenovic. Wiley. 2008
  • How to Make Money in Alternative Investments. Hubert and Lisa Moren Bromma. McGraw-Hill. 2010

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