The device you're using to read this comment couldn't function without gold. It's an incredibly useful element. Investment and speculation might have inflated the value of gold, but industrial demand sets a price floor.

Si is also incredibly useful but requires industrial processing to turn into something useful from an industrial standpoint.

Au is indeed useful, but not so much as nearly indicated by its current pricing. There's a _long_ history of human predilection for gold-as-a-magical-substance versus gold-as-an-industrially-useful-element.

Gold has rarely been used in retail transactions. Generally that's been limited to silver, copper, bronze, or even iron coins, or other materials.

Not exclusively, but for the large part.

If you look at historical English prices, prior to the 19th century, the penny was 1/240 a pound, and the farthing ("four-thing" -- one fourth a penny) was 1/960 a pound. Call it 1/1000th.

A labourer's wage might be 20 pound/yr. It's more useful to think of the farthing as roughly equivalent, at least in work-time, to a dollar, and 20 pound as $20,000.

A pound, then, was a lot of money. And even it was (in English currency) silver. Gold were guineas: 1 pound 10 shilling.