What use would gold be in a financial crash?

If there was a total collapse of the financial system, it could be used in a barter aspect in place of money. Yes, it would probably technically have a “dollar value”, but if the dollar is worthless, there’d be no reason to trade it in on dollars or euros or anything like that. Also, if the US dollar collapsed but something like the Chinese Renminbi was still strong, you could likely sell the gold for that currency.

Negligible. You’d need to store it someplace safe, and then you would have to be able to access it before you could even think about trading it in.

You also need to prove its authenticity at every step of the process. That cost money.
Counterfeiters are geting better at it every day. Counterfeit gold bars. This scam started with real bars, hollowed them out and filled them with tungsten to get the same mass.
I heard of totally fake bars made of a tungsten sponge and filled with lead to get the exact mass and density. The bar is then gold plated.
(We made a device that looked for the acoustic signature resulting from a standard impact. When struck, a gold bar has a distinctive frequency output that has not been duplicated with other metals or alloys – so far.)

The idea is that financial systems will/way tend to survive a financial crash in such a way that after it, gold is likely to still be valuable, while the money you used to buy it before the crash, has much less value after the crash.

Your money has no intrinsic value. It’s propped up by the faith people have in Gov’t and financial institutions. If that faith gets rattled, your “money” vanishes. Gold has intrinsic value so whatever the new “money” ends up being, gold can be converted to it. Gold is good for storing large amounts of wealth. It is not good for bartering. If you want something to barter with, silver coins work, as does anything “fungible.” That could be small bottles of liquor, ammunition, packs of toilet paper, or just about any commodity with an inelastic intrinsic value at the level of common things you need to trade for regularly.

The proposition is that the value of gold would not lose all of its value, and could continue to be used for trade.
But it will lose value nonetheless, and the value it retains will be based on others’ willingness to accept it as payment. In essence, its usefulness as currency is just as much based on collective trust as paper money is.
You should collect bottlecaps instead. Or bullets.

In a financial crash, you typically have deflation, which increases the value of your money relative to goods and services.

This is because financial crashes are typically precipitated by too much private debt at an accelerating rate. You get a moment when everyone rushes to deleverage their debts (sell assets to pay them off) which shrinks the money supply (all money is basically bank issued credit).

If anything, you get more people hoarding cash without spending it, as there’s no incentive to spend when prices keep dropping. The velocity of money drops, aggregate demand drops, unemployment rises, and everyone waits for the government to intervene by injecting liquidity into the economy.

This is what happened in Germany in the late 1920s, everywhere else in the 1930s, and more recently in 2007/2008.

Gold’s value during any sort of economic crash is purely psychological, and often revolves around fears of hyperinflation or the supposed lack of real value of money. Its price is maintained or even raised because enough people believe it will store value, and so those who can afford it will buy it.

Salt used to be used as money is now. There will always be something to trade that someone wants.

The US dollar is the only currency (not bitcoins, or bullion) in the world that one can pay tax debt to the US government. That means there will always be an intrinsic worth to the US dollar.