Copper is not a reasonable intermediary of trade except for small goods because of its supply/demand curve. There is just too much supply. On the other side, gold is also not a reasonable intermediary of trade except for large goods (really large goods, like battleships, or skyscrapers, or countries) because of its supply/demand curve. There is just too little supply.

The supply/demand curve of silver is what makes silver so good for the most common purchases people make, from weekly groceries to buying cars or even houses.

At least this is true according to the "official numbers" of these items. I have no idea how accurate those numbers are. However, just based on nuclear physics the amount of gold to silver to copper does reasonably match the relative amounts suggested by those official numbers, so even if the real supplies are all multiplied by 10, the ratios are probably about right.

Copper is not a reasonable intermediary of trade except for small goods because of its supply/demand curve. There is just too much supply. On the other side, gold is also not a reasonable intermediary of trade except for large goods (really large goods, like battleships, or skyscrapers, or countries) because of its supply/demand curve. There is just too little supply.

The supply/demand curve of silver is what makes silver so good for the most common purchases people make, from weekly groceries to buying cars or even houses.

At least this is true according to the "official numbers" of these items. I have no idea how accurate those numbers are. However, just based on nuclear physics the amount of gold to silver to copper does reasonably match the relative amounts suggested by those official numbers, so even the real supplies are all multiplied by 10, the ratios are probably about right.