Interesting that it misses what I always thought was the most important property of gold in this regard which is that it is (for a pre-technological society at least) completely unadulterable. It's the densest material you can readily obtain, without the ability to smelt platinum (whose melting point issues were mentioned in the article as a disqualifier for functioning as money). That means that I can't make a coin that matches both the size and the weight of a real gold coin out of anything other than gold. If you'd picked iron as the precious metal, I could fake an iron coin by mixing tin and lead together so the alloy's density matches iron's. But to make a fake gold coin without using gold, I need to mix something lighter than it with something heavier - and my options looking for something heavier are either in the platinum group, or are heavy radioisotopes like Uranium. All of which are probably sufficiently rare in a pre-technological society that they're worth more than their weight in gold anyway, so not much use as raw materials in a forgery. Density is destiny...?