They asked for the most delicate silk and the purest gold thread, put both into their own knapsacks, and then continued their pretended work at the empty looms until late at night.
This is about 85% pure gold, but it could also be found like this, and this is a gold nugget that was found in a river, on a river bed, and it's a heavy piece of gold.
The chemicals extract what's inside and produce this brown powder. It's then heated for 30 minutes at more than 1,000 degrees Celsius. The end result is pure gold!
They realised that the answer was for the state to mint coins of pure gold and pure silver, of consistent weights that would have absolutely reliable value.