The most detailed study of an asteroid shows that it contains precious metals worth at least $20,000bn.
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If Eros is typical of stony meteorites, then it contains about 3% metal. With the known abundance's of metals in meteorites, even a very cautious estimate suggests 20,000 million tonnes of aluminium along with similar amounts of gold, platinum and other rarer metals.
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In the 2,900 cubic kms of Eros, there is more aluminium, gold, silver, zinc and other base and precious metals than have ever been excavated in history or indeed, could ever be excavated from the upper layers of the Earth's crust.
That is just in one asteroid and not a very large one at that. There are thousands of asteroids out there.
Astronomic value
How much is Eros worth? Today's trading price for gold is about $250 per ounce or about $9m per tonne.
It means the value of the gold in asteroid Eros is about $1,000bn. That is just the gold. Platinum is even more expensive, $350 per oz. Work it out yourself. Since it contains a lot of rare elements and metals that are of use in the semiconductor industry for example, at today's prices Eros is worth more than $20,000bn.