Silver vs Gold

Silver has been mined, hoarded and argued over for at least five thousand years. It is soft enough to shape with simple tools, bright enough to work as a mirror, and rare enough to serve as money. For most of recorded history those were its jobs: coins, cutlery, jewellery and ornament.

• Silver tarnishes not because of oxygen but because of tiny amounts of hydrogen sulfide in the air, which form a dark layer of silver sulfide.
• Polished silver reflects more visible light than any other metal, which is why it was used to back the earliest glass mirrors.

Gold objects buried more than six thousand years ago come out of the ground as bright as the day they were made. That single property, a near total refusal to react with air or water, explains almost everything about gold's place in history. It could be found as pure metal in riverbeds, shaped without a furnace, and it never lost its shine. So it became ornament, then money, then the standard against which money was measured.

• All the gold ever mined, well over 200,000 tonnes, would fit in a cube roughly 22 metres on each side.
• Gold is so malleable that a single gram can be beaten into a sheet about a square metre in area, and gold leaf is thin enough for greenish light to pass through it.