In addition, there are eighteen gold radioisotopes, so the amount of gold in the universe is decreasing as they decay.
In addition, not all of the gold on earth has been discovered, much less the whole universe. We also don't know how much the ultimate amount might be, so the amount of gold in known existence is not stable.
Regardless, the use of gold simply because of its relative stability of existence is ridiculous. While you might not be able to change its amount, you can still alter the amount of purchasing power it commands by altering the amount of purchasing power available.
Gold standard promoters claim that all fiat currencies have failed. There are very few countries in the world that don't have fiat currencies, and their currencies have not failed, making the claim prima facie false.
Please do your own research into the matter.
Ron Paul is not a promoter of some "gold standard", he's a promoter of using tangible commodities for currency. Gold happens to be a commodity that has been widely supported historically, so it gets much attention from Paul and investors in precious metals.
"claim that all fiat currencies have failed."
The claim is that all fiat currencies *eventually* fail.
"There are very few countries in the world that don't have fiat currencies, and their currencies have not failed, making the claim prima facie false."
Either you're arguing against yourself, or "their" was supposed to refer to countries *with* fiat currencies. Regardless, your argument is as unsound as claiming that humans are immortal because many humans are alive today.
"Please do your own research into the matter."
Please help us get started. Cite a reference, give us something to google. Otherwise you're copping out and hoping somebody else can support your claim for you, when you apparently can't yourself.