When gold is sharply up, that means that currency is expected to be worth less. When gold is sharply down, that means that currency is expected to be worth more.
I think gold reached its pinnacle and then amalgams were invented to create new teeth. That was the beginning of the end.
Another way to look at gold, is as an indicator of ability to trade goods.
When more able, then "producing one's way out of the hole" may be relied upon. When less able, then selling assets is more relied upon.
Because we would hope to hang on to our assets by which we produce, it helps to have something to trade. Gold is handy at such times.