The price of gold over time is a good thing to study. One thing that will jump out at you is that gold has never gone to zero. The current price of gold has always been determined by supply and demand. So, when the economy is down along with stocks, demand for gold is usually steady and gold will retain it's value.

There is a very large amount of stored gold with affects the supply. Investors will usually buy gold as a hedge against uncertainty in the economic or political theater. Any world crises will undoubtedly affect the price of gold along with the demand for it.

One must assume that there is a finite amount of gold in the ground and that is one of the reasons the price of gold over time has remained stable. Production of gold continues on with new findings happening all the time but this will not last forever. Besides people hoarding gold it is also used for jewelry and dental work so it does have real uses along with just being pretty.