system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why is gold the standard of wealth when things like iron, wood, or food may be more useful and fossils (ie) may be just as rare.
gpt
A few reasons:

1. Gold is rare. If you're going to use something as a medium of exchange, you need it to have a stable supply. You want to know that when you accept a gold coin for your goods or service, it will still have a similar value next year when you spend it. 

2. Gold doesn't tarnish, so you can store value. Iron rusts, wood rots, food spoils. We still find gold coins from the ancient world that are in good shape today.

3. Gold is very dense. At the time it started to be used as a currency, it was the most dense metal known. This made it impossible to counterfeit, as any additives would decrease the weight of the coin and be immediately identifiable. 

4. Gold is easy to work with. It is soft and melts at a relatively low temperature. If you decide your gold coins are too big, you can easily melt them down and recast them into smaller coins.